x86: hyperv: Add mshv_handler() irq handler and setup function

Add mshv_handler() to process messages related to managing guest
partitions such as intercepts, doorbells, and scheduling messages.

In

x86: hyperv: Add mshv_handler() irq handler and setup function

Add mshv_handler() to process messages related to managing guest
partitions such as intercepts, doorbells, and scheduling messages.

In a (non-nested) root partition, the same interrupt vector is shared
between the vmbus and mshv_root drivers.

Introduce a stub for mshv_handler() and call it in
sysvec_hyperv_callback alongside vmbus_handler().

Even though both handlers will be called for every Hyper-V interrupt,
the messages for each driver are delivered to different offsets
within the SYNIC message page, so they won't step on each other.

Signed-off-by: Nuno Das Neves <[email protected]>
Reviewed-by: Wei Liu <[email protected]>
Reviewed-by: Tianyu Lan <[email protected]>
Reviewed-by: Stanislav Kinsburskii <[email protected]>
Link: https://lore.kernel.org/r/1741980536-3865-9-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <1741980536-3865-9-git-send-email-nunodasneves@linux.microsoft.com>

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Drivers: hv: Export some functions for use by root partition module

hv_get_hypervisor_version(), hv_call_deposit_pages(), and
hv_call_create_vp(), are all needed in-module with CONFIG_MSHV_ROOT=m.

Drivers: hv: Export some functions for use by root partition module

hv_get_hypervisor_version(), hv_call_deposit_pages(), and
hv_call_create_vp(), are all needed in-module with CONFIG_MSHV_ROOT=m.

Signed-off-by: Nuno Das Neves <[email protected]>
Reviewed-by: Stanislav Kinsburskii <[email protected]>
Reviewed-by: Roman Kisel <[email protected]>
Reviewed-by: Easwar Hariharan <[email protected]>
Reviewed-by: Tianyu Lan <[email protected]>
Link: https://lore.kernel.org/r/1741980536-3865-7-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <1741980536-3865-7-git-send-email-nunodasneves@linux.microsoft.com>

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x86/mshyperv: Add support for extended Hyper-V features

Extend the "ms_hyperv_info" structure to include a new field,
"ext_features", for capturing extended Hyper-V features.
Update the "ms_hyperv_i

x86/mshyperv: Add support for extended Hyper-V features

Extend the "ms_hyperv_info" structure to include a new field,
"ext_features", for capturing extended Hyper-V features.
Update the "ms_hyperv_init_platform" function to retrieve these features
using the cpuid instruction and include them in the informational output.

Signed-off-by: Stanislav Kinsburskii <[email protected]>
Signed-off-by: Nuno Das Neves <[email protected]>
Reviewed-by: Easwar Hariharan <[email protected]>
Reviewed-by: Roman Kisel <[email protected]>
Reviewed-by: Tianyu Lan <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/1741980536-3865-3-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <1741980536-3865-3-git-send-email-nunodasneves@linux.microsoft.com>

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hyperv: Change hv_root_partition into a function

Introduce hv_curr_partition_type to store the partition type
as an enum.

Right now this is limited to guest or root partition, but there will
be oth

hyperv: Change hv_root_partition into a function

Introduce hv_curr_partition_type to store the partition type
as an enum.

Right now this is limited to guest or root partition, but there will
be other kinds in future and the enum is easily extensible.

Set up hv_curr_partition_type early in Hyper-V initialization with
hv_identify_partition_type(). hv_root_partition() just queries this
value, and shouldn't be called before that.

Making this check into a function sets the stage for adding a config
option to gate the compilation of root partition code. In particular,
hv_root_partition() can be stubbed out always be false if root
partition support isn't desired.

Signed-off-by: Nuno Das Neves <[email protected]>
Reviewed-by: Easwar Hariharan <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/1740167795-13296-3-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <1740167795-13296-3-git-send-email-nunodasneves@linux.microsoft.com>

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hyperv: Switch from hyperv-tlfs.h to hyperv/hvhdk.h

Switch to using hvhdk.h everywhere in the kernel. This header
includes all the new Hyper-V headers in include/hyperv, which form a
superset of the

hyperv: Switch from hyperv-tlfs.h to hyperv/hvhdk.h

Switch to using hvhdk.h everywhere in the kernel. This header
includes all the new Hyper-V headers in include/hyperv, which form a
superset of the definitions found in hyperv-tlfs.h.

This makes it easier to add new Hyper-V interfaces without being
restricted to those in the TLFS doc (reflected in hyperv-tlfs.h).

To be more consistent with the original Hyper-V code, the names of
some definitions are changed slightly. Update those where needed.

Update comments in mshyperv.h files to point to include/hyperv for
adding new definitions.

Signed-off-by: Nuno Das Neves <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Reviewed-by: Easwar Hariharan <[email protected]>
Signed-off-by: Roman Kisel <[email protected]>
Reviewed-by: Easwar Hariharan <[email protected]>
Link: https://lore.kernel.org/r/1732577084-2122-5-git-send-email-nunodasneves@linux.microsoft.com
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>

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x86/hyperv: Fix hv tsc page based sched_clock for hibernation

read_hv_sched_clock_tsc() assumes that the Hyper-V clock counter is
bigger than the variable hv_sched_clock_offset, which is cached duri

x86/hyperv: Fix hv tsc page based sched_clock for hibernation

read_hv_sched_clock_tsc() assumes that the Hyper-V clock counter is
bigger than the variable hv_sched_clock_offset, which is cached during
early boot, but depending on the timing this assumption may be false
when a hibernated VM starts again (the clock counter starts from 0
again) and is resuming back (Note: hv_init_tsc_clocksource() is not
called during hibernation/resume); consequently,
read_hv_sched_clock_tsc() may return a negative integer (which is
interpreted as a huge positive integer since the return type is u64)
and new kernel messages are prefixed with huge timestamps before
read_hv_sched_clock_tsc() grows big enough (which typically takes
several seconds).

Fix the issue by saving the Hyper-V clock counter just before the
suspend, and using it to correct the hv_sched_clock_offset in
resume. This makes hv tsc page based sched_clock continuous and ensures
that post resume, it starts from where it left off during suspend.
Override x86_platform.save_sched_clock_state and
x86_platform.restore_sched_clock_state routines to correct this as soon
as possible.

Note: if Invariant TSC is available, the issue doesn't happen because
1) we don't register read_hv_sched_clock_tsc() for sched clock:
See commit e5313f1c5404 ("clocksource/drivers/hyper-v: Rework
clocksource and sched clock setup");
2) the common x86 code adjusts TSC similarly: see
__restore_processor_state() -> tsc_verify_tsc_adjust(true) and
x86_platform.restore_sched_clock_state().

Cc: [email protected]
Fixes: 1349401ff1aa ("clocksource/drivers/hyper-v: Suspend/resume Hyper-V clocksource for hibernation")
Co-developed-by: Dexuan Cui <[email protected]>
Signed-off-by: Dexuan Cui <[email protected]>
Signed-off-by: Naman Jain <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <[email protected]>

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x86/hyperv: fix kexec crash due to VP assist page corruption

commit 9636be85cc5b ("x86/hyperv: Fix hyperv_pcpu_input_arg handling when
CPUs go online/offline") introduces a new cpuhp state for hyper

x86/hyperv: fix kexec crash due to VP assist page corruption

commit 9636be85cc5b ("x86/hyperv: Fix hyperv_pcpu_input_arg handling when
CPUs go online/offline") introduces a new cpuhp state for hyperv
initialization.

cpuhp_setup_state() returns the state number if state is
CPUHP_AP_ONLINE_DYN or CPUHP_BP_PREPARE_DYN and 0 for all other states.
For the hyperv case, since a new cpuhp state was introduced it would
return 0. However, in hv_machine_shutdown(), the cpuhp_remove_state() call
is conditioned upon "hyperv_init_cpuhp > 0". This will never be true and
so hv_cpu_die() won't be called on all CPUs. This means the VP assist page
won't be reset. When the kexec kernel tries to setup the VP assist page
again, the hypervisor corrupts the memory region of the old VP assist page
causing a panic in case the kexec kernel is using that memory elsewhere.
This was originally fixed in commit dfe94d4086e4 ("x86/hyperv: Fix kexec
panic/hang issues").

Get rid of hyperv_init_cpuhp entirely since we are no longer using a
dynamic cpuhp state and use CPUHP_AP_HYPERV_ONLINE directly with
cpuhp_remove_state().

Cc: [email protected]
Fixes: 9636be85cc5b ("x86/hyperv: Fix hyperv_pcpu_input_arg handling when CPUs go online/offline")
Signed-off-by: Anirudh Rayabharam (Microsoft) <[email protected]>
Reviewed-by: Vitaly Kuznetsov <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <[email protected]>

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x86/hyperv: Set X86_FEATURE_TSC_KNOWN_FREQ when Hyper-V provides frequency

A Linux guest on Hyper-V gets the TSC frequency from a synthetic MSR, if
available. In this case, set X86_FEATURE_TSC_KNOWN

x86/hyperv: Set X86_FEATURE_TSC_KNOWN_FREQ when Hyper-V provides frequency

A Linux guest on Hyper-V gets the TSC frequency from a synthetic MSR, if
available. In this case, set X86_FEATURE_TSC_KNOWN_FREQ so that Linux
doesn't unnecessarily do refined TSC calibration when setting up the TSC
clocksource.

With this change, a message such as this is no longer output during boot
when the TSC is used as the clocksource:

[ 1.115141] tsc: Refined TSC clocksource calibration: 2918.408 MHz

Furthermore, the guest and host will have exactly the same view of the
TSC frequency, which is important for features such as the TSC deadline
timer that are emulated by the Hyper-V host.

Signed-off-by: Michael Kelley <[email protected]>
Reviewed-by: Roman Kisel <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <[email protected]>

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clockevents/drivers/i8253: Fix stop sequence for timer 0

According to the data sheet, writing the MODE register should stop the
counter (and thus the interrupts). This appears to work on real hardwa

clockevents/drivers/i8253: Fix stop sequence for timer 0

According to the data sheet, writing the MODE register should stop the
counter (and thus the interrupts). This appears to work on real hardware,
at least modern Intel and AMD systems. It should also work on Hyper-V.

However, on some buggy virtual machines the mode change doesn't have any
effect until the counter is subsequently loaded (or perhaps when the IRQ
next fires).

So, set MODE 0 and then load the counter, to ensure that those buggy VMs
do the right thing and the interrupts stop. And then write MODE 0 *again*
to stop the counter on compliant implementations too.

Apparently, Hyper-V keeps firing the IRQ *repeatedly* even in mode zero
when it should only happen once, but the second MODE write stops that too.

Userspace test program (mostly written by tglx):
=====
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdint.h>
#include <sys/io.h>

static __always_inline void __out##bwl(type value, uint16_t port) \
{ \
asm volatile("out" #bwl " %" #bw "0, %w1" \
: : "a"(value), "Nd"(port)); \
} \
\
static __always_inline type __in##bwl(uint16_t port) \
{ \
type value; \
asm volatile("in" #bwl " %w1, %" #bw "0" \
: "=a"(value) : "Nd"(port)); \
return value; \
}

BUILDIO(b, b, uint8_t)

#define inb __inb
#define outb __outb

#define PIT_MODE 0x43
#define PIT_CH0 0x40
#define PIT_CH2 0x42

static int is8254;

static void dump_pit(void)
{
if (is8254) {
// Latch and output counter and status
outb(0xC2, PIT_MODE);
printf("%02x %02x %02x\n", inb(PIT_CH0), inb(PIT_CH0), inb(PIT_CH0));
} else {
// Latch and output counter
outb(0x0, PIT_MODE);
printf("%02x %02x\n", inb(PIT_CH0), inb(PIT_CH0));
}
}

int main(int argc, char* argv[])
{
int nr_counts = 2;

if (argc > 1)
nr_counts = atoi(argv[1]);

if (argc > 2)
is8254 = 1;

if (ioperm(0x40, 4, 1) != 0)
return 1;

dump_pit();

printf("Set oneshot\n");
outb(0x38, PIT_MODE);
outb(0x00, PIT_CH0);
outb(0x0F, PIT_CH0);

dump_pit();
usleep(1000);
dump_pit();

printf("Set periodic\n");
outb(0x34, PIT_MODE);
outb(0x00, PIT_CH0);
outb(0x0F, PIT_CH0);

dump_pit();
usleep(1000);
dump_pit();
dump_pit();
usleep(100000);
dump_pit();
usleep(100000);
dump_pit();

printf("Set stop (%d counter writes)\n", nr_counts);
outb(0x30, PIT_MODE);
while (nr_counts--)
outb(0xFF, PIT_CH0);

dump_pit();
usleep(100000);
dump_pit();
usleep(100000);
dump_pit();

printf("Set MODE 0\n");
outb(0x30, PIT_MODE);

dump_pit();
usleep(100000);
dump_pit();
usleep(100000);
dump_pit();

return 0;
}
=====

Suggested-by: Sean Christopherson <[email protected]>
Co-developed-by: Li RongQing <[email protected]>
Signed-off-by: Li RongQing <[email protected]>
Signed-off-by: David Woodhouse <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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clocksource: hyper-v: Use lapic timer in a TDX VM without paravisor

In a TDX VM without paravisor, currently the default timer is the Hyper-V
timer, which depends on the slow VM Reference Counter MS

clocksource: hyper-v: Use lapic timer in a TDX VM without paravisor

In a TDX VM without paravisor, currently the default timer is the Hyper-V
timer, which depends on the slow VM Reference Counter MSR: the Hyper-V TSC
page is not enabled in such a VM because the VM uses Invariant TSC as a
better clocksource and it's challenging to mark the Hyper-V TSC page shared
in very early boot.

Lower the rating of the Hyper-V timer so the local APIC timer becomes the
the default timer in such a VM, and print a warning in case Invariant TSC
is unavailable in such a VM. This change should cause no perceivable
performance difference.

Cc: [email protected] # 6.6+
Reviewed-by: Roman Kisel <[email protected]>
Signed-off-by: Dexuan Cui <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <[email protected]>

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x86/hyperv: Use Hyper-V entropy to seed guest random number generator

A Hyper-V host provides its guest VMs with entropy in a custom ACPI
table named "OEM0". The entropy bits are updated each time

x86/hyperv: Use Hyper-V entropy to seed guest random number generator

A Hyper-V host provides its guest VMs with entropy in a custom ACPI
table named "OEM0". The entropy bits are updated each time Hyper-V
boots the VM, and are suitable for seeding the Linux guest random
number generator (rng). See a brief description of OEM0 in [1].

Generation 2 VMs on Hyper-V use UEFI to boot. Existing EFI code in
Linux seeds the rng with entropy bits from the EFI_RNG_PROTOCOL.
Via this path, the rng is seeded very early during boot with good
entropy. The ACPI OEM0 table provided in such VMs is an additional
source of entropy.

Generation 1 VMs on Hyper-V boot from BIOS. For these VMs, Linux
doesn't currently get any entropy from the Hyper-V host. While this
is not fundamentally broken because Linux can generate its own entropy,
using the Hyper-V host provided entropy would get the rng off to a
better start and would do so earlier in the boot process.

Improve the rng seeding for Generation 1 VMs by having Hyper-V specific
code in Linux take advantage of the OEM0 table to seed the rng. For
Generation 2 VMs, use the OEM0 table to provide additional entropy
beyond the EFI_RNG_PROTOCOL. Because the OEM0 table is custom to
Hyper-V, parse it directly in the Hyper-V code in the Linux kernel
and use add_bootloader_randomness() to add it to the rng. Once the
entropy bits are read from OEM0, zero them out in the table so
they don't appear in /sys/firmware/acpi/tables/OEM0 in the running
VM. The zero'ing is done out of an abundance of caution to avoid
potential security risks to the rng. Also set the OEM0 data length
to zero so a kexec or other subsequent use of the table won't try
to use the zero'ed bits.

[1] https://download.microsoft.com/download/1/c/9/1c9813b8-089c-4fef-b2ad-ad80e79403ba/Whitepaper%20-%20The%20Windows%2010%20random%20number%20generation%20infrastructure.pdf

Signed-off-by: Michael Kelley <[email protected]>
Reviewed-by: Jason A. Donenfeld <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <[email protected]>

show more ...

hyperv-tlfs: Rename some HV_REGISTER_* defines for consistency

Rename HV_REGISTER_GUEST_OSID to HV_REGISTER_GUEST_OS_ID. This matches
the existing HV_X64_MSR_GUEST_OS_ID.

Rename HV_REGISTER_CRASH_*

hyperv-tlfs: Rename some HV_REGISTER_* defines for consistency

Rename HV_REGISTER_GUEST_OSID to HV_REGISTER_GUEST_OS_ID. This matches
the existing HV_X64_MSR_GUEST_OS_ID.

Rename HV_REGISTER_CRASH_* to HV_REGISTER_GUEST_CRASH_*. Including
GUEST_ is consistent with other #defines such as
HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE. The new names also match the TLFS
document more accurately, i.e. HvRegisterGuestCrash*.

Signed-off-by: Nuno Das Neves <[email protected]>
Link: https://lore.kernel.org/r/1710285687-9160-1-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <1710285687-9160-1-git-send-email-nunodasneves@linux.microsoft.com>

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mshyperv: Introduce hv_get_hypervisor_version function

Introduce x86_64 and arm64 functions to get the hypervisor version
information and store it in a structure for simpler parsing.

Use the new fu

mshyperv: Introduce hv_get_hypervisor_version function

Introduce x86_64 and arm64 functions to get the hypervisor version
information and store it in a structure for simpler parsing.

Use the new function to get and parse the version at boot time. While at
it, move the printing code to hv_common_init() so it is not duplicated.

Signed-off-by: Nuno Das Neves <[email protected]>
Acked-by: Wei Liu <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/1709852618-29110-1-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <1709852618-29110-1-git-send-email-nunodasneves@linux.microsoft.com>

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hyperv-tlfs: Change prefix of generic HV_REGISTER_* MSRs to HV_MSR_*

The HV_REGISTER_ are used as arguments to hv_set/get_register(), which
delegate to arch-specific mechanisms for getting/setting s

hyperv-tlfs: Change prefix of generic HV_REGISTER_* MSRs to HV_MSR_*

The HV_REGISTER_ are used as arguments to hv_set/get_register(), which
delegate to arch-specific mechanisms for getting/setting synthetic
Hyper-V MSRs.

On arm64, HV_REGISTER_ defines are synthetic VP registers accessed via
the get/set vp registers hypercalls. The naming matches the TLFS
document, although these register names are not specific to arm64.

However, on x86 the prefix HV_REGISTER_ indicates Hyper-V MSRs accessed
via rdmsrl()/wrmsrl(). This is not consistent with the TLFS doc, where
HV_REGISTER_ is *only* used for used for VP register names used by
the get/set register hypercalls.

To fix this inconsistency and prevent future confusion, change the
arch-generic aliases used by callers of hv_set/get_register() to have
the prefix HV_MSR_ instead of HV_REGISTER_.

Use the prefix HV_X64_MSR_ for the x86-only Hyper-V MSRs. On x86, the
generic HV_MSR_'s point to the corresponding HV_X64_MSR_.

Move the arm64 HV_REGISTER_* defines to the asm-generic hyperv-tlfs.h,
since these are not specific to arm64. On arm64, the generic HV_MSR_'s
point to the corresponding HV_REGISTER_.

While at it, rename hv_get/set_registers() and related functions to
hv_get/set_msr(), hv_get/set_nested_msr(), etc. These are only used for
Hyper-V MSRs and this naming makes that clear.

Signed-off-by: Nuno Das Neves <[email protected]>
Reviewed-by: Wei Liu <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/1708440933-27125-1-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <1708440933-27125-1-git-send-email-nunodasneves@linux.microsoft.com>

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x86, crash: wrap crash dumping code into crash related ifdefs

Now crash codes under kernel/ folder has been split out from kexec
code, crash dumping can be separated from kexec reboot in config
item

x86, crash: wrap crash dumping code into crash related ifdefs

Now crash codes under kernel/ folder has been split out from kexec
code, crash dumping can be separated from kexec reboot in config
items on x86 with some adjustments.

Here, also change some ifdefs or IS_ENABLED() check to more appropriate
ones, e,g
- #ifdef CONFIG_KEXEC_CORE -> #ifdef CONFIG_CRASH_DUMP
- (!IS_ENABLED(CONFIG_KEXEC_CORE)) - > (!IS_ENABLED(CONFIG_CRASH_RESERVE))

[[email protected]: don't nest CONFIG_CRASH_DUMP ifdef inside CONFIG_KEXEC_CODE ifdef scope]
Link: https://lore.kernel.org/all/SN6PR02MB4157931105FA68D72E3D3DB8D47B2@SN6PR02MB4157.namprd02.prod.outlook.com/T/#u
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Baoquan He <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Eric W. Biederman <[email protected]>
Cc: Hari Bathini <[email protected]>
Cc: Pingfan Liu <[email protected]>
Cc: Klara Modin <[email protected]>
Cc: Michael Kelley <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Yang Li <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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x86/traps: Add sysvec_install() to install a system interrupt handler

Add sysvec_install() to install a system interrupt handler into the IDT
or the FRED system interrupt handler table.

Signed-off-

x86/traps: Add sysvec_install() to install a system interrupt handler

Add sysvec_install() to install a system interrupt handler into the IDT
or the FRED system interrupt handler table.

Signed-off-by: Xin Li <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Tested-by: Shan Kang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/hyperv: Use atomic_try_cmpxchg() to micro-optimize hv_nmi_unknown()

Use atomic_try_cmpxchg() instead of atomic_cmpxchg(*ptr, old, new) == old
in hv_nmi_unknown(). On x86 the CMPXCHG instruction

x86/hyperv: Use atomic_try_cmpxchg() to micro-optimize hv_nmi_unknown()

Use atomic_try_cmpxchg() instead of atomic_cmpxchg(*ptr, old, new) == old
in hv_nmi_unknown(). On x86 the CMPXCHG instruction returns success in
the ZF flag, so this change saves a compare after CMPXCHG. The generated
asm code improves from:

3e: 65 8b 15 00 00 00 00 mov %gs:0x0(%rip),%edx
45: b8 ff ff ff ff mov $0xffffffff,%eax
4a: f0 0f b1 15 00 00 00 lock cmpxchg %edx,0x0(%rip)
51: 00
52: 83 f8 ff cmp $0xffffffff,%eax
55: 0f 95 c0 setne %al

to:

3e: 65 8b 15 00 00 00 00 mov %gs:0x0(%rip),%edx
45: b8 ff ff ff ff mov $0xffffffff,%eax
4a: f0 0f b1 15 00 00 00 lock cmpxchg %edx,0x0(%rip)
51: 00
52: 0f 95 c0 setne %al

No functional change intended.

Cc: "K. Y. Srinivasan" <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Cc: Wei Liu <[email protected]>
Cc: Dexuan Cui <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Signed-off-by: Uros Bizjak <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <[email protected]>

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x86/hyperv: Remove hv_isolation_type_en_snp

In ms_hyperv_init_platform(), do not distinguish between a SNP VM with
the paravisor and a SNP VM without the paravisor.

Replace hv_isolation_type_en_snp

x86/hyperv: Remove hv_isolation_type_en_snp

In ms_hyperv_init_platform(), do not distinguish between a SNP VM with
the paravisor and a SNP VM without the paravisor.

Replace hv_isolation_type_en_snp() with
!ms_hyperv.paravisor_present && hv_isolation_type_snp().

The hv_isolation_type_en_snp() in drivers/hv/hv.c and
drivers/hv/hv_common.c can be changed to hv_isolation_type_snp() since
we know !ms_hyperv.paravisor_present is true there.

Signed-off-by: Dexuan Cui <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Reviewed-by: Tianyu Lan <[email protected]>
Signed-off-by: Wei Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/hyperv: Use TDX GHCI to access some MSRs in a TDX VM with the paravisor

When the paravisor is present, a SNP VM must use GHCB to access some
special MSRs, including HV_X64_MSR_GUEST_OS_ID and so

x86/hyperv: Use TDX GHCI to access some MSRs in a TDX VM with the paravisor

When the paravisor is present, a SNP VM must use GHCB to access some
special MSRs, including HV_X64_MSR_GUEST_OS_ID and some SynIC MSRs.

Similarly, when the paravisor is present, a TDX VM must use TDX GHCI
to access the same MSRs.

Implement hv_tdx_msr_write() and hv_tdx_msr_read(), and use the helper
functions hv_ivm_msr_read() and hv_ivm_msr_write() to access the MSRs
in a unified way for SNP/TDX VMs with the paravisor.

Do not export hv_tdx_msr_write() and hv_tdx_msr_read(), because we never
really used hv_ghcb_msr_write() and hv_ghcb_msr_read() in any module.

Update arch/x86/include/asm/mshyperv.h so that the kernel can still build
if CONFIG_AMD_MEM_ENCRYPT or CONFIG_INTEL_TDX_GUEST is not set, or
neither is set.

Signed-off-by: Dexuan Cui <[email protected]>
Reviewed-by: Tianyu Lan <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Signed-off-by: Wei Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/hyperv: Introduce a global variable hyperv_paravisor_present

The new variable hyperv_paravisor_present is set only when the VM
is a SNP/TDX VM with the paravisor running: see ms_hyperv_init_plat

x86/hyperv: Introduce a global variable hyperv_paravisor_present

The new variable hyperv_paravisor_present is set only when the VM
is a SNP/TDX VM with the paravisor running: see ms_hyperv_init_platform().

We introduce hyperv_paravisor_present because we can not use
ms_hyperv.paravisor_present in arch/x86/include/asm/mshyperv.h:

struct ms_hyperv_info is defined in include/asm-generic/mshyperv.h, which
is included at the end of arch/x86/include/asm/mshyperv.h, but at the
beginning of arch/x86/include/asm/mshyperv.h, we would already need to use
struct ms_hyperv_info in hv_do_hypercall().

We use hyperv_paravisor_present only in include/asm-generic/mshyperv.h,
and use ms_hyperv.paravisor_present elsewhere. In the future, we'll
introduce a hypercall function structure for different VM types, and
at boot time, the right function pointers would be written into the
structure so that runtime testing of TDX vs. SNP vs. normal will be
avoided and hyperv_paravisor_present will no longer be needed.

Call hv_vtom_init() when it's a VBS VM or when ms_hyperv.paravisor_present
is true, i.e. the VM is a SNP VM or TDX VM with the paravisor.

Enhance hv_vtom_init() for a TDX VM with the paravisor.

In hv_common_cpu_init(), don't decrypt the hyperv_pcpu_input_arg
for a TDX VM with the paravisor, just like we don't decrypt the page
for a SNP VM with the paravisor.

Signed-off-by: Dexuan Cui <[email protected]>
Reviewed-by: Tianyu Lan <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Signed-off-by: Wei Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/hyperv: Fix serial console interrupts for fully enlightened TDX guests

When a fully enlightened TDX guest runs on Hyper-V, the UEFI firmware sets
the HW_REDUCED flag and consequently ttyS0 inter

x86/hyperv: Fix serial console interrupts for fully enlightened TDX guests

When a fully enlightened TDX guest runs on Hyper-V, the UEFI firmware sets
the HW_REDUCED flag and consequently ttyS0 interrupts can't work. Fix the
issue by overriding x86_init.acpi.reduced_hw_early_init().

Reviewed-by: Michael Kelley <[email protected]>
Reviewed-by: Tianyu Lan <[email protected]>
Signed-off-by: Dexuan Cui <[email protected]>
Signed-off-by: Wei Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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Drivers: hv: vmbus: Support fully enlightened TDX guests

Add Hyper-V specific code so that a fully enlightened TDX guest (i.e.
without the paravisor) can run on Hyper-V:
Don't use hv_vp_assist_pag

Drivers: hv: vmbus: Support fully enlightened TDX guests

Add Hyper-V specific code so that a fully enlightened TDX guest (i.e.
without the paravisor) can run on Hyper-V:
Don't use hv_vp_assist_page. Use GHCI instead.
Don't try to use the unsupported HV_REGISTER_CRASH_CTL.
Don't trust (use) Hyper-V's TLB-flushing hypercalls.
Don't use lazy EOI.
Share the SynIC Event/Message pages with the hypervisor.
Don't use the Hyper-V TSC page for now, because non-trivial work is
required to share the page with the hypervisor.

Reviewed-by: Michael Kelley <[email protected]>
Signed-off-by: Dexuan Cui <[email protected]>
Signed-off-by: Wei Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/hyperv: Add hv_isolation_type_tdx() to detect TDX guests

No logic change to SNP/VBS guests.

hv_isolation_type_tdx() will be used to instruct a TDX guest on Hyper-V to
do some TDX-specific opera

x86/hyperv: Add hv_isolation_type_tdx() to detect TDX guests

No logic change to SNP/VBS guests.

hv_isolation_type_tdx() will be used to instruct a TDX guest on Hyper-V to
do some TDX-specific operations, e.g. for a fully enlightened TDX guest
(i.e. without the paravisor), hv_do_hypercall() should use
__tdx_hypercall() and such a guest on Hyper-V should handle the Hyper-V
Event/Message/Monitor pages specially.

Reviewed-by: Michael Kelley <[email protected]>
Reviewed-by: Tianyu Lan <[email protected]>
Signed-off-by: Dexuan Cui <[email protected]>
Signed-off-by: Wei Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/hyperv: Fix undefined reference to isolation_type_en_snp without CONFIG_HYPERV

When CONFIG_HYPERV is not set, arch/x86/hyperv/ivm.c is not built (see
arch/x86/Kbuild), so 'isolation_type_en_snp'

x86/hyperv: Fix undefined reference to isolation_type_en_snp without CONFIG_HYPERV

When CONFIG_HYPERV is not set, arch/x86/hyperv/ivm.c is not built (see
arch/x86/Kbuild), so 'isolation_type_en_snp' in the ivm.c is not defined,
and this failure happens:

ld: arch/x86/kernel/cpu/mshyperv.o: in function `ms_hyperv_init_platform':
arch/x86/kernel/cpu/mshyperv.c:417: undefined reference to `isolation_type_en_snp'

Fix the failure by testing hv_get_isolation_type() and
ms_hyperv.paravisor_present for a fully enlightened SNP VM: when
CONFIG_HYPERV is not set, hv_get_isolation_type() is defined as a
static inline function that always returns HV_ISOLATION_TYPE_NONE
(see include/asm-generic/mshyperv.h), so the compiler won't generate any
code for the ms_hyperv.paravisor_present and static_branch_enable().

Reported-by: Tom Lendacky <[email protected]>
Closes: https://lore.kernel.org/lkml/[email protected]/
Fixes: d6e2d6524437 ("x86/hyperv: Add sev-snp enlightened guest static key")
Signed-off-by: Dexuan Cui <[email protected]>
Signed-off-by: Wei Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/hyperv: Add hyperv-specific handling for VMMCALL under SEV-ES

Add Hyperv-specific handling for faults caused by VMMCALL
instructions.

Reviewed-by: Dexuan Cui <[email protected]>
Reviewed-by:

x86/hyperv: Add hyperv-specific handling for VMMCALL under SEV-ES

Add Hyperv-specific handling for faults caused by VMMCALL
instructions.

Reviewed-by: Dexuan Cui <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Signed-off-by: Tianyu Lan <[email protected]>
Signed-off-by: Wei Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...