KVM: Allow page-sized MMU caches to be initialized with custom 64-bit values

Add support to MMU caches for initializing a page with a custom 64-bit
value, e.g. to pre-fill an entire page table with

KVM: Allow page-sized MMU caches to be initialized with custom 64-bit values

Add support to MMU caches for initializing a page with a custom 64-bit
value, e.g. to pre-fill an entire page table with non-zero PTE values.
The functionality will be used by x86 to support Intel's TDX, which needs
to set bit 63 in all non-present PTEs in order to prevent !PRESENT page
faults from getting reflected into the guest (Intel's EPT Violation #VE
architecture made the less than brilliant decision of having the per-PTE
behavior be opt-out instead of opt-in).

Signed-off-by: Sean Christopherson <[email protected]>
Signed-off-by: Isaku Yamahata <[email protected]>
Message-Id: <5919f685f109a1b0ebc6bd8fc4536ee94bcc172d.1705965635.git.isaku.yamahata@intel.com>
Reviewed-by: Xiaoyao Li <[email protected]>
Reviewed-by: Binbin Wu <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: pfncache: remove KVM_GUEST_USES_PFN usage

As noted in [1] the KVM_GUEST_USES_PFN usage flag is never set by any
callers of kvm_gpc_init(), and for good reason: the implementation is
incomplete/

KVM: pfncache: remove KVM_GUEST_USES_PFN usage

As noted in [1] the KVM_GUEST_USES_PFN usage flag is never set by any
callers of kvm_gpc_init(), and for good reason: the implementation is
incomplete/broken. And it's not clear that there will ever be a user of
KVM_GUEST_USES_PFN, as coordinating vCPUs with mmu_notifier events is
non-trivial.

Remove KVM_GUEST_USES_PFN and all related code, e.g. dropping
KVM_GUEST_USES_PFN also makes the 'vcpu' argument redundant, to avoid
having to reason about broken code as __kvm_gpc_refresh() evolves.

Moreover, all existing callers specify KVM_HOST_USES_PFN so the usage
check in hva_to_pfn_retry() and hence the 'usage' argument to
kvm_gpc_init() are also redundant.

[1] https://lore.kernel.org/all/[email protected]

Signed-off-by: Paul Durrant <[email protected]>
Reviewed-by: David Woodhouse <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[sean: explicitly call out that guest usage is incomplete]
Signed-off-by: Sean Christopherson <[email protected]>

show more ...

KVM: Convert KVM_ARCH_WANT_MMU_NOTIFIER to CONFIG_KVM_GENERIC_MMU_NOTIFIER

Convert KVM_ARCH_WANT_MMU_NOTIFIER into a Kconfig and select it where
appropriate to effectively maintain existing behavior

KVM: Convert KVM_ARCH_WANT_MMU_NOTIFIER to CONFIG_KVM_GENERIC_MMU_NOTIFIER

Convert KVM_ARCH_WANT_MMU_NOTIFIER into a Kconfig and select it where
appropriate to effectively maintain existing behavior. Using a proper
Kconfig will simplify building more functionality on top of KVM's
mmu_notifier infrastructure.

Add a forward declaration of kvm_gfn_range to kvm_types.h so that
including arch/powerpc/include/asm/kvm_ppc.h's with CONFIG_KVM=n doesn't
generate warnings due to kvm_gfn_range being undeclared. PPC defines
hooks for PR vs. HV without guarding them via #ifdeffery, e.g.

bool (*unmap_gfn_range)(struct kvm *kvm, struct kvm_gfn_range *range);
bool (*age_gfn)(struct kvm *kvm, struct kvm_gfn_range *range);
bool (*test_age_gfn)(struct kvm *kvm, struct kvm_gfn_range *range);
bool (*set_spte_gfn)(struct kvm *kvm, struct kvm_gfn_range *range);

Alternatively, PPC could forward declare kvm_gfn_range, but there's no
good reason not to define it in common KVM.

Acked-by: Anup Patel <[email protected]>
Signed-off-by: Sean Christopherson <[email protected]>
Reviewed-by: Paolo Bonzini <[email protected]>
Reviewed-by: Fuad Tabba <[email protected]>
Tested-by: Fuad Tabba <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: Shrink struct kvm_mmu_memory_cache

Move the 'capacity' member around to make use of the padding hole on 64
bit systems instead of introducing yet another one.

This allows us to save 8 bytes pe

KVM: Shrink struct kvm_mmu_memory_cache

Move the 'capacity' member around to make use of the padding hole on 64
bit systems instead of introducing yet another one.

This allows us to save 8 bytes per instance for 64 bit builds of which,
e.g., x86's struct kvm_vcpu_arch has a few.

Signed-off-by: Mathias Krause <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>

show more ...

KVM: MMU: Make the definition of 'INVALID_GPA' common

KVM already has a 'GPA_INVALID' defined as (~(gpa_t)0) in kvm_types.h,
and it is used by ARM code. We do not need another definition of
'INVALID

KVM: MMU: Make the definition of 'INVALID_GPA' common

KVM already has a 'GPA_INVALID' defined as (~(gpa_t)0) in kvm_types.h,
and it is used by ARM code. We do not need another definition of
'INVALID_GPA' for X86 specifically.

Instead of using the common 'GPA_INVALID' for X86, replace it with
'INVALID_GPA', and change the users of 'GPA_INVALID' so that the diff
can be smaller. Also because the name 'INVALID_GPA' tells the user we
are using an invalid GPA, while the name 'GPA_INVALID' is emphasizing
the GPA is an invalid one.

No functional change intended.

Signed-off-by: Yu Zhang <[email protected]>
Reviewed-by: Paul Durrant <[email protected]>
Reviewed-by: Sean Christopherson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Oliver Upton <[email protected]>

show more ...

KVM: Store immutable gfn_to_pfn_cache properties

Move the assignment of immutable properties @kvm, @vcpu, and @usage to
the initializer. Make _activate() and _deactivate() use stored values.

Note,

KVM: Store immutable gfn_to_pfn_cache properties

Move the assignment of immutable properties @kvm, @vcpu, and @usage to
the initializer. Make _activate() and _deactivate() use stored values.

Note, @len is also effectively immutable for most cases, but not in the
case of the Xen runstate cache, which may be split across two pages and
the length of the first segment will depend on its address.

Suggested-by: Sean Christopherson <[email protected]>
Signed-off-by: Michal Luczaj <[email protected]>
[sean: handle @len in a separate patch]
Signed-off-by: Sean Christopherson <[email protected]>
[dwmw2: acknowledge that @len can actually change for some use cases]
Signed-off-by: David Woodhouse <[email protected]>

show more ...

KVM: Add gfp_custom flag in struct kvm_mmu_memory_cache

The kvm_mmu_topup_memory_cache() always uses GFP_KERNEL_ACCOUNT for
memory allocation which prevents it's use in atomic context. To address
th

KVM: Add gfp_custom flag in struct kvm_mmu_memory_cache

The kvm_mmu_topup_memory_cache() always uses GFP_KERNEL_ACCOUNT for
memory allocation which prevents it's use in atomic context. To address
this limitation of kvm_mmu_topup_memory_cache(), we add gfp_custom flag
in struct kvm_mmu_memory_cache. When the gfp_custom flag is set to some
GFP_xyz flags, the kvm_mmu_topup_memory_cache() will use that instead of
GFP_KERNEL_ACCOUNT.

Signed-off-by: Anup Patel <[email protected]>
Reviewed-by: Atish Patra <[email protected]>
Signed-off-by: Anup Patel <[email protected]>

show more ...

KVM: Allow for different capacities in kvm_mmu_memory_cache structs

Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
declaration time rather than being fixed for all declaration

KVM: Allow for different capacities in kvm_mmu_memory_cache structs

Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
declaration time rather than being fixed for all declarations. This will
be used in a follow-up commit to declare an cache in x86 with a capacity
of 512+ objects without having to increase the capacity of all caches in
KVM.

This change requires each cache now specify its capacity at runtime,
since the cache struct itself no longer has a fixed capacity known at
compile time. To protect against someone accidentally defining a
kvm_mmu_memory_cache struct directly (without the extra storage), this
commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().

In order to support different capacities, this commit changes the
objects pointer array to be dynamically allocated the first time the
cache is topped-up.

While here, opportunistically clean up the stack-allocated
kvm_mmu_memory_cache structs in riscv and arm64 to use designated
initializers.

No functional change intended.

Reviewed-by: Marc Zyngier <[email protected]>
Signed-off-by: David Matlack <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: Fully serialize gfn=>pfn cache refresh via mutex

Protect gfn=>pfn cache refresh with a mutex to fully serialize refreshes.
The refresh logic doesn't protect against

- concurrent unmaps, or ref

KVM: Fully serialize gfn=>pfn cache refresh via mutex

Protect gfn=>pfn cache refresh with a mutex to fully serialize refreshes.
The refresh logic doesn't protect against

- concurrent unmaps, or refreshes with different GPAs (which may or may not
happen in practice, for example if a cache is only used under vcpu->mutex;
but it's allowed in the code)

- a false negative on the memslot generation. If the first refresh sees
a stale memslot generation, it will refresh the hva and generation before
moving on to the hva=>pfn translation. If it then drops gpc->lock, a
different user of the cache can come along, acquire gpc->lock, see that
the memslot generation is fresh, and skip the hva=>pfn update due to the
userspace address also matching (because it too was updated).

The refresh path can already sleep during hva=>pfn resolution, so wrap
the refresh with a mutex to ensure that any given refresh runs to
completion before other callers can start their refresh.

Cc: [email protected]
Cc: Lai Jiangshan <[email protected]>
Signed-off-by: Sean Christopherson <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: Remove dirty handling from gfn_to_pfn_cache completely

It isn't OK to cache the dirty status of a page in internal structures
for an indefinite period of time.

Any time a vCPU exits the run lo

KVM: Remove dirty handling from gfn_to_pfn_cache completely

It isn't OK to cache the dirty status of a page in internal structures
for an indefinite period of time.

Any time a vCPU exits the run loop to userspace might be its last; the
VMM might do its final check of the dirty log, flush the last remaining
dirty pages to the destination and complete a live migration. If we
have internal 'dirty' state which doesn't get flushed until the vCPU
is finally destroyed on the source after migration is complete, then
we have lost data because that will escape the final copy.

This problem already exists with the use of kvm_vcpu_unmap() to mark
pages dirty in e.g. VMX nesting.

Note that the actual Linux MM already considers the page to be dirty
since we have a writeable mapping of it. This is just about the KVM
dirty logging.

For the nesting-style use cases (KVM_GUEST_USES_PFN) we will need to
track which gfn_to_pfn_caches have been used and explicitly mark the
corresponding pages dirty before returning to userspace. But we would
have needed external tracking of that anyway, rather than walking the
full list of GPCs to find those belonging to this vCPU which are dirty.

So let's rely *solely* on that external tracking, and keep it simple
rather than laying a tempting trap for callers to fall into.

Signed-off-by: David Woodhouse <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: Use enum to track if cached PFN will be used in guest and/or host

Replace the guest_uses_pa and kernel_map booleans in the PFN cache code
with a unified enum/bitmask. Using explicit names makes

KVM: Use enum to track if cached PFN will be used in guest and/or host

Replace the guest_uses_pa and kernel_map booleans in the PFN cache code
with a unified enum/bitmask. Using explicit names makes it easier to
review and audit call sites.

Opportunistically add a WARN to prevent passing garbage; instantating a
cache without declaring its usage is either buggy or pointless.

Signed-off-by: Sean Christopherson <[email protected]>
Signed-off-by: David Woodhouse <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: Reinstate gfn_to_pfn_cache with invalidation support

This can be used in two modes. There is an atomic mode where the cached
mapping is accessed while holding the rwlock, and a mode where the
p

KVM: Reinstate gfn_to_pfn_cache with invalidation support

This can be used in two modes. There is an atomic mode where the cached
mapping is accessed while holding the rwlock, and a mode where the
physical address is used by a vCPU in guest mode.

For the latter case, an invalidation will wake the vCPU with the new
KVM_REQ_GPC_INVALIDATE, and the architecture will need to refresh any
caches it still needs to access before entering guest mode again.

Only one vCPU can be targeted by the wake requests; it's simple enough
to make it wake all vCPUs or even a mask but I don't see a use case for
that additional complexity right now.

Invalidation happens from the invalidate_range_start MMU notifier, which
needs to be able to sleep in order to wake the vCPU and wait for it.

This means that revalidation potentially needs to "wait" for the MMU
operation to complete and the invalidate_range_end notifier to be
invoked. Like the vCPU when it takes a page fault in that period, we
just spin — fixing that in a future patch by implementing an actual
*wait* may be another part of shaving this particularly hirsute yak.

As noted in the comments in the function itself, the only case where
the invalidate_range_start notifier is expected to be called *without*
being able to sleep is when the OOM reaper is killing the process. In
that case, we expect the vCPU threads already to have exited, and thus
there will be nothing to wake, and no reason to wait. So we clear the
KVM_REQUEST_WAIT bit and send the request anyway, then complain loudly
if there actually *was* anything to wake up.

Signed-off-by: David Woodhouse <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: stats: Add stat to detect if vcpu is currently blocking

Add a "blocking" stat that userspace can use to detect the case where a
vCPU is not being run because of an vCPU/guest action, e.g. HLT o

KVM: stats: Add stat to detect if vcpu is currently blocking

Add a "blocking" stat that userspace can use to detect the case where a
vCPU is not being run because of an vCPU/guest action, e.g. HLT or WFS on
x86, WFI on arm64, etc... Current guest/host/halt stats don't show this
well, e.g. if a guest halts for a long period of time then the vCPU could
could appear pathologically blocked due to a host condition, when in
reality the vCPU has been put into a not-runnable state by the guest.

Originally-by: Cannon Matthews <[email protected]>
Suggested-by: Sean Christopherson <[email protected]>
Reviewed-by: David Matlack <[email protected]>
Signed-off-by: Jing Zhang <[email protected]>
[sean: renamed stat to "blocking", massaged changelog]
Signed-off-by: Sean Christopherson <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: Kill kvm_map_gfn() / kvm_unmap_gfn() and gfn_to_pfn_cache

In commit 7e2175ebd695 ("KVM: x86: Fix recording of guest steal time /
preempted status") I removed the only user of these functions be

KVM: Kill kvm_map_gfn() / kvm_unmap_gfn() and gfn_to_pfn_cache

In commit 7e2175ebd695 ("KVM: x86: Fix recording of guest steal time /
preempted status") I removed the only user of these functions because
it was basically impossible to use them safely.

There are two stages to the GFN->PFN mapping; first through the KVM
memslots to a userspace HVA and then through the page tables to
translate that HVA to an underlying PFN. Invalidations of the former
were being handled correctly, but no attempt was made to use the MMU
notifiers to invalidate the cache when the HVA->GFN mapping changed.

As a prelude to reinventing the gfn_to_pfn_cache with more usable
semantics, rip it out entirely and untangle the implementation of
the unsafe kvm_vcpu_map()/kvm_vcpu_unmap() functions from it.

All current users of kvm_vcpu_map() also look broken right now, and
will be dealt with separately. They broadly fall into two classes:

* Those which map, access the data and immediately unmap. This is
mostly gratuitous and could just as well use the existing user
HVA, and could probably benefit from a gfn_to_hva_cache as they
do so.

* Those which keep the mapping around for a longer time, perhaps
even using the PFN directly from the guest. These will need to
be converted to the new gfn_to_pfn_cache and then kvm_vcpu_map()
can be removed too.

Signed-off-by: David Woodhouse <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: stats: Add VM stat for remote tlb flush requests

Add a new stat that counts the number of times a remote TLB flush is
requested, regardless of whether it kicks vCPUs out of guest mode. This
all

KVM: stats: Add VM stat for remote tlb flush requests

Add a new stat that counts the number of times a remote TLB flush is
requested, regardless of whether it kicks vCPUs out of guest mode. This
allows us to look at how often flushes are initiated.

Unlike remote_tlb_flush, this one applies to ARM's instruction-set-based
TLB flush implementation, so apply it there too.

Original-by: David Matlack <[email protected]>
Signed-off-by: Jing Zhang <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: stats: Add halt polling related histogram stats

Add three log histogram stats to record the distribution of time spent
on successful polling, failed polling and VCPU wait.
halt_poll_success_his

KVM: stats: Add halt polling related histogram stats

Add three log histogram stats to record the distribution of time spent
on successful polling, failed polling and VCPU wait.
halt_poll_success_hist: Distribution of spent time for a successful poll.
halt_poll_fail_hist: Distribution of spent time for a failed poll.
halt_wait_hist: Distribution of time a VCPU has spent on waiting.

Signed-off-by: Jing Zhang <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: stats: Add halt_wait_ns stats for all architectures

Add simple stats halt_wait_ns to record the time a VCPU has spent on
waiting for all architectures (not just powerpc).

Signed-off-by: Jing Z

KVM: stats: Add halt_wait_ns stats for all architectures

Add simple stats halt_wait_ns to record the time a VCPU has spent on
waiting for all architectures (not just powerpc).

Signed-off-by: Jing Zhang <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: stats: Add fd-based API to read binary stats data

This commit defines the API for userspace and prepare the common
functionalities to support per VM/VCPU binary stats data readings.

The KVM st

KVM: stats: Add fd-based API to read binary stats data

This commit defines the API for userspace and prepare the common
functionalities to support per VM/VCPU binary stats data readings.

The KVM stats now is only accessible by debugfs, which has some
shortcomings this change series are supposed to fix:
1. The current debugfs stats solution in KVM could be disabled
when kernel Lockdown mode is enabled, which is a potential
rick for production.
2. The current debugfs stats solution in KVM is organized as "one
stats per file", it is good for debugging, but not efficient
for production.
3. The stats read/clear in current debugfs solution in KVM are
protected by the global kvm_lock.

Besides that, there are some other benefits with this change:
1. All KVM VM/VCPU stats can be read out in a bulk by one copy
to userspace.
2. A schema is used to describe KVM statistics. From userspace's
perspective, the KVM statistics are self-describing.
3. With the fd-based solution, a separate telemetry would be able
to read KVM stats in a less privileged environment.
4. After the initial setup by reading in stats descriptors, a
telemetry only needs to read the stats data itself, no more
parsing or setup is needed.

Reviewed-by: David Matlack <[email protected]>
Reviewed-by: Ricardo Koller <[email protected]>
Reviewed-by: Krish Sadhukhan <[email protected]>
Reviewed-by: Fuad Tabba <[email protected]>
Tested-by: Fuad Tabba <[email protected]> #arm64
Signed-off-by: Jing Zhang <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: stats: Separate generic stats from architecture specific ones

Generic KVM stats are those collected in architecture independent code
or those supported by all architectures; put all generic sta

KVM: stats: Separate generic stats from architecture specific ones

Generic KVM stats are those collected in architecture independent code
or those supported by all architectures; put all generic statistics in
a separate structure. This ensures that they are defined the same way
in the statistics API which is being added, removing duplication among
different architectures in the declaration of the descriptors.

No functional change intended.

Reviewed-by: David Matlack <[email protected]>
Reviewed-by: Ricardo Koller <[email protected]>
Reviewed-by: Krish Sadhukhan <[email protected]>
Signed-off-by: Jing Zhang <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: Move x86's version of struct kvm_mmu_memory_cache to common code

Move x86's 'struct kvm_mmu_memory_cache' to common code in anticipation
of moving the entire x86 implementation code to common K

KVM: Move x86's version of struct kvm_mmu_memory_cache to common code

Move x86's 'struct kvm_mmu_memory_cache' to common code in anticipation
of moving the entire x86 implementation code to common KVM and reusing
it for arm64 and MIPS. Add a new architecture specific asm/kvm_types.h
to control the existence and parameters of the struct. The new header
is needed to avoid a chicken-and-egg problem with asm/kvm_host.h as all
architectures define instances of the struct in their vCPU structs.

Add an asm-generic version of kvm_types.h to avoid having empty files on
PPC and s390 in the long term, and for arm64 and mips in the short term.

Suggested-by: Christoffer Dall <[email protected]>
Reviewed-by: Ben Gardon <[email protected]>
Signed-off-by: Sean Christopherson <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

x86/kvm: Cache gfn to pfn translation

__kvm_map_gfn()'s call to gfn_to_pfn_memslot() is
* relatively expensive
* in certain cases (such as when done from atomic context) cannot be called

Stashing g

x86/kvm: Cache gfn to pfn translation

__kvm_map_gfn()'s call to gfn_to_pfn_memslot() is
* relatively expensive
* in certain cases (such as when done from atomic context) cannot be called

Stashing gfn-to-pfn mapping should help with both cases.

This is part of CVE-2019-3016.

Signed-off-by: Boris Ostrovsky <[email protected]>
Reviewed-by: Joao Martins <[email protected]>
Cc: [email protected]
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

KVM: arm64: Support stolen time reporting via shared structure

Implement the service call for configuring a shared structure between a
VCPU and the hypervisor in which the hypervisor can write the t

KVM: arm64: Support stolen time reporting via shared structure

Implement the service call for configuring a shared structure between a
VCPU and the hypervisor in which the hypervisor can write the time
stolen from the VCPU's execution time by other tasks on the host.

User space allocates memory which is placed at an IPA also chosen by user
space. The hypervisor then updates the shared structure using
kvm_put_guest() to ensure single copy atomicity of the 64-bit value
reporting the stolen time in nanoseconds.

Whenever stolen time is enabled by the guest, the stolen time counter is
reset.

The stolen time itself is retrieved from the sched_info structure
maintained by the Linux scheduler code. We enable SCHEDSTATS when
selecting KVM Kconfig to ensure this value is meaningful.

Signed-off-by: Steven Price <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>

show more ...

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 503

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of th

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 503

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license this
program is distributed in the hope that it will be useful but
without any warranty without even the implied warranty of
merchantability or fitness for a particular purpose see the gnu
general public license for more details you should have received a
copy of the gnu general public license along with this program if
not write to the free software foundation 51 franklin street fifth
floor boston ma 02110 1301 usa

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 1 file(s).

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Kate Stewart <[email protected]>
Reviewed-by: Allison Randal <[email protected]>
Reviewed-by: Enrico Weigelt <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

kvm: rename pfn_t to kvm_pfn_t

To date, we have implemented two I/O usage models for persistent memory,
PMEM (a persistent "ram disk") and DAX (mmap persistent memory into
userspace). This series a

kvm: rename pfn_t to kvm_pfn_t

To date, we have implemented two I/O usage models for persistent memory,
PMEM (a persistent "ram disk") and DAX (mmap persistent memory into
userspace). This series adds a third, DAX-GUP, that allows DAX mappings
to be the target of direct-i/o. It allows userspace to coordinate
DMA/RDMA from/to persistent memory.

The implementation leverages the ZONE_DEVICE mm-zone that went into
4.3-rc1 (also discussed at kernel summit) to flag pages that are owned
and dynamically mapped by a device driver. The pmem driver, after
mapping a persistent memory range into the system memmap via
devm_memremap_pages(), arranges for DAX to distinguish pfn-only versus
page-backed pmem-pfns via flags in the new pfn_t type.

The DAX code, upon seeing a PFN_DEV+PFN_MAP flagged pfn, flags the
resulting pte(s) inserted into the process page tables with a new
_PAGE_DEVMAP flag. Later, when get_user_pages() is walking ptes it keys
off _PAGE_DEVMAP to pin the device hosting the page range active.
Finally, get_page() and put_page() are modified to take references
against the device driver established page mapping.

Finally, this need for "struct page" for persistent memory requires
memory capacity to store the memmap array. Given the memmap array for a
large pool of persistent may exhaust available DRAM introduce a
mechanism to allocate the memmap from persistent memory. The new
"struct vmem_altmap *" parameter to devm_memremap_pages() enables
arch_add_memory() to use reserved pmem capacity rather than the page
allocator.

This patch (of 18):

The core has developed a need for a "pfn_t" type [1]. Move the existing
pfn_t in KVM to kvm_pfn_t [2].

[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002199.html
[2]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002218.html

Signed-off-by: Dan Williams <[email protected]>
Acked-by: Christoffer Dall <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

KVM: add memslots argument to kvm_arch_memslots_updated

Prepare for the case of multiple address spaces.

Reviewed-by: Radim Krcmar <[email protected]>
Signed-off-by: Paolo Bonzini <pbonzini@redhat

KVM: add memslots argument to kvm_arch_memslots_updated

Prepare for the case of multiple address spaces.

Reviewed-by: Radim Krcmar <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...