- 24 Jun, 2022 17 commits
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David Matlack authored
Consolidate kvm_mmu_alloc_page() and kvm_mmu_alloc_shadow_page() under the latter so that all shadow page allocation and initialization happens in one place. No functional change intended. Signed-off-by:
David Matlack <dmatlack@google.com> Message-Id: <20220516232138.1783324-8-dmatlack@google.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com>
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David Matlack authored
Decompose kvm_mmu_get_page() into separate helper functions to increase readability and prepare for allocating shadow pages without a vcpu pointer. Specifically, pull the guts of kvm_mmu_get_page() into 2 helper functions: kvm_mmu_find_shadow_page() - Walks the page hash checking for any existing mmu pages that match the given gfn and role. kvm_mmu_alloc_shadow_page() Allocates and initializes an entirely new kvm_mmu_page. This currently requries a vcpu pointer for allocation and looking up the memslot but that will be removed in a future commit. No functional change intended. Reviewed-by:
Sean Christopherson <seanjc@google.com> Signed-off-by:
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David Matlack authored
The quadrant is only used when gptes are 4 bytes, but mmu_alloc_{direct,shadow}_roots() pass in a non-zero quadrant for PAE page directories regardless. Make this less confusing by only passing in a non-zero quadrant when it is actually necessary. Signed-off-by: -
David Matlack authored
Instead of computing the shadow page role from scratch for every new page, derive most of the information from the parent shadow page. This eliminates the dependency on the vCPU root role to allocate shadow page tables, and reduces the number of parameters to kvm_mmu_get_page(). Preemptively split out the role calculation to a separate function for use in a following commit. Note that when calculating the MMU root role, we can take @role.passthrough, @role.direct, and @role.access directly from @vcpu->arch.mmu->root_role. Only @role.level and @role.quadrant still must be overridden for PAE page directories, when shadowing 32-bit guest page tables with PAE page tables. No functional change intended. Reviewed-by:
Peter Xu <peterx@redhat.com> Signed-off-by:
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David Matlack authored
The "direct" argument is vcpu->arch.mmu->root_role.direct, because unlike non-root page tables, it's impossible to have a direct root in an indirect MMU. So just use that. Suggested-by:
Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by:
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David Matlack authored
The parameter "direct" can either be true or false, and all of the callers pass in a bool variable or true/false literal, so just use the type bool. No functional change intended. Reviewed-by:
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David Matlack authored
Commit fb58a9c3 ("KVM: x86/mmu: Optimize MMU page cache lookup for fully direct MMUs") skipped the unsync checks and write flood clearing for full direct MMUs. We can extend this further to skip the checks for all direct shadow pages. Direct shadow pages in indirect MMUs (i.e. shadow paging) are used when shadowing a guest huge page with smaller pages. Such direct shadow pages, like their counterparts in fully direct MMUs, are never marked unsynced or have a non-zero write-flooding count. Checking sp->role.direct also generates better code than checking direct_map because, due to register pressure, direct_map has to get shoved onto the stack and then pulled back off. No functional change intended. Reviewed-by:
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Ben Gardon authored
In order to improve performance across multiple reads of VM stats, cache the stats metadata in the VM struct. Signed-off-by:
Ben Gardon <bgardon@google.com> Message-Id: <20220613212523.3436117-11-bgardon@google.com> Signed-off-by:
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Ben Gardon authored
Add an argument to the NX huge pages test to test disabling the feature on a VM using the new capability. Reviewed-by:
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Ben Gardon authored
There's currently no test coverage of NX hugepages in KVM selftests, so add a basic test to ensure that the feature works as intended. The test creates a VM with a data slot backed with huge pages. The memory in the data slot is filled with op-codes for the return instruction. The guest then executes a series of accesses on the memory, some reads, some instruction fetches. After each operation, the guest exits and the test performs some checks on the backing page counts to ensure that NX page splitting an reclaim work as expected. Reviewed-by:
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Ben Gardon authored
In some cases, the NX hugepage mitigation for iTLB multihit is not needed for all guests on a host. Allow disabling the mitigation on a per-VM basis to avoid the performance hit of NX hugepages on trusted workloads. In order to disable NX hugepages on a VM, ensure that the userspace actor has permission to reboot the system. Since disabling NX hugepages would allow a guest to crash the system, it is similar to reboot permissions. Ideally, KVM would require userspace to prove it has access to KVM's nx_huge_pages module param, e.g. so that userspace can opt out without needing full reboot permissions. But getting access to the module param file info is difficult because it is buried in layers of sysfs and module glue. Requiring CAP_SYS_BOOT is sufficient for all known use cases. Suggested-by:
Jim Mattson <jmattson@google.com> Reviewed-by:
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Ben Gardon authored
The braces around the KVM_CAP_XSAVE2 block also surround the KVM_CAP_PMU_CAPABILITY block, likely the result of a merge issue. Simply move the curly brace back to where it belongs. Fixes: ba7bb663 ("KVM: x86: Provide per VM capability for disabling PMU virtualization") Reviewed-by:
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Ben Gardon authored
Move the code to read the binary stats data to the KVM selftests library. It will be re-used by other tests to check KVM behavior. Also opportunistically remove an unnecessary calculation with "size_data" in stats_test. Reviewed-by:
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Sean Christopherson authored
Fix a variety of code style violations and/or inconsistencies in the binary stats test. The 80 char limit is a soft limit and can and should be ignored/violated if doing so improves the overall code readability. Specifically, provide consistent indentation and don't split expressions at arbitrary points just to honor the 80 char limit. Opportunistically expand/add comments to call out the more subtle aspects of the code. Signed-off-by:
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Ben Gardon authored
Move the code to read the binary stats descriptors to the KVM selftests library. It will be re-used by other tests to check KVM behavior. No functional change intended. Reviewed-by:
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Ben Gardon authored
Move the code to read the binary stats header to the KVM selftests library. It will be re-used by other tests to check KVM behavior. No functional change intended. Reviewed-by:
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Ben Gardon authored
There's no need to allocate dynamic memory for the stats header since its size is known at compile time. Reviewed-by:
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- 22 Jun, 2022 1 commit
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Sean Christopherson authored
Add a test to verify the "MONITOR/MWAIT never fault" quirk, and as a bonus, also verify the related "MISC_ENABLES ignores ENABLE_MWAIT" quirk. If the "never fault" quirk is enabled, MONITOR/MWAIT should always be emulated as NOPs, even if they're reported as disabled in guest CPUID. Use the MISC_ENABLES quirk to coerce KVM into toggling the MWAIT CPUID enable, as KVM now disallows manually toggling CPUID bits after running the vCPU. Signed-off-by:
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- 20 Jun, 2022 22 commits
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Sean Christopherson authored
Use exception fixup to verify VMCALL/RDMSR/WRMSR fault as expected in the Hyper-V Features test. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Explicitly do all setup at every stage of the Hyper-V Features test, e.g. set the MSR/hypercall, enable capabilities, etc... Now that the VM is recreated for every stage, values that are written into the VM's address space, i.e. shared with the guest, are reset between sub-tests, as are any capabilities, etc... Fix the hypercall params as well, which were broken in the same rework. The "hcall" struct/pointer needs to point at the hcall_params object, not the set of hypercall pages. The goofs were hidden by the test's dubious behavior of using '0' to signal "done", i.e. the MSR test ran exactly one sub-test, and the hypercall test was a gigantic nop. Fixes: 6c118643 ("KVM: selftests: Avoid KVM_SET_CPUID2 after KVM_RUN in hyperv_features test") Signed-off-by:
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Sean Christopherson authored
Add x86-64 support for exception fixup on single instructions, without forcing tests to install their own fault handlers. Use registers r9-r11 to flag the instruction as "safe" and pass fixup/vector information, i.e. introduce yet another flavor of fixup (versus the kernel's in-memory tables and KUT's per-CPU area) to take advantage of KVM sefltests being 64-bit only. Using only registers avoids the need to allocate fixup tables, ensure FS or GS base is valid for the guest, ensure memory is mapped into the guest, etc..., and also reduces the potential for recursive faults due to accessing memory. Providing exception fixup trivializes tests that just want to verify that an instruction faults, e.g. no need to track start/end using global labels, no need to install a dedicated handler, etc... Deliberately do not support #DE in exception fixup so that the fixup glue doesn't need to account for a fault with vector == 0, i.e. the vector can also indicate that a fault occurred. KVM injects #DE only for esoteric emulation scenarios, i.e. there's very, very little value in testing #DE. Force any test that wants to generate #DEs to install its own handler(s). Use kvm_pv_test as a guinea pig for the new fixup, as it has a very straightforward use case of wanting to verify that RDMSR and WRMSR fault. Signed-off-by:
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Sean Christopherson authored
Add a quirk for KVM's behavior of emulating intercepted MONITOR/MWAIT instructions a NOPs regardless of whether or not they are supported in guest CPUID. KVM's current behavior was likely motiviated by a certain fruity operating system that expects MONITOR/MWAIT to be supported unconditionally and blindly executes MONITOR/MWAIT without first checking CPUID. And because KVM does NOT advertise MONITOR/MWAIT to userspace, that's effectively the default setup for any VMM that regurgitates KVM_GET_SUPPORTED_CPUID to KVM_SET_CPUID2. Note, this quirk interacts with KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT. The behavior is actually desirable, as userspace VMMs that want to unconditionally hide MONITOR/MWAIT from the guest can leave the MISC_ENABLE quirk enabled. Signed-off-by:
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Sean Christopherson authored
Ignore host userspace writes of '0' to F15H_PERF_CTL MSRs KVM reports in the MSR-to-save list, but the MSRs are ultimately unsupported. All MSRs in said list must be writable by userspace, e.g. if userspace sends the list back at KVM without filtering out the MSRs it doesn't need. Note, reads of said MSRs already have the desired behavior. Signed-off-by:
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Sean Christopherson authored
Ignore host userspace reads and writes of '0' to PEBS and BTS MSRs that KVM reports in the MSR-to-save list, but the MSRs are ultimately unsupported. All MSRs in said list must be writable by userspace, e.g. if userspace sends the list back at KVM without filtering out the MSRs it doesn't need. Fixes: 8183a538 ("KVM: x86/pmu: Add IA32_DS_AREA MSR emulation to support guest DS") Fixes: 902caeb6 ("KVM: x86/pmu: Add PEBS_DATA_CFG MSR emulation to support adaptive PEBS") Fixes: c59a1f10 ("KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS") Signed-off-by:
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Sean Christopherson authored
Use vcpu_get_perf_capabilities() when querying MSR_IA32_PERF_CAPABILITIES from the guest's perspective, e.g. to update the vPMU and to determine which MSRs exist. If userspace ignores MSR_IA32_PERF_CAPABILITIES but clear X86_FEATURE_PDCM, the guest should see '0'. Fixes: 902caeb6 ("KVM: x86/pmu: Add PEBS_DATA_CFG MSR emulation to support adaptive PEBS") Fixes: c59a1f10 ("KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS") Signed-off-by:
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Sean Christopherson authored
Revert the hack to allow host-initiated accesses to all "PMU" MSRs, as intel_is_valid_msr() returns true for _all_ MSRs, regardless of whether or not it has a snowball's chance in hell of actually being a PMU MSR. That mostly gets papered over by the actual get/set helpers only handling MSRs that they knows about, except there's the minor detail that kvm_pmu_{g,s}et_msr() eat reads and writes when the PMU is disabled. I.e. KVM will happy allow reads and writes to _any_ MSR if the PMU is disabled, either via module param or capability. This reverts commit d1c88a40. Fixes: d1c88a40 ("KVM: x86: always allow host-initiated writes to PMU MSRs") Signed-off-by: -
Sean Christopherson authored
Eating reads and writes to all "PMU" MSRs when there is no PMU is wildly broken as it results in allowing accesses to _any_ MSR on Intel CPUs as intel_is_valid_msr() returns true for all host_initiated accesses. A revert of commit d1c88a40 ("KVM: x86: always allow host-initiated writes to PMU MSRs") will soon follow. This reverts commit 8e6a58e2. Signed-off-by:
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Sean Christopherson authored
Do not clear manipulate MSR_IA32_PERF_CAPABILITIES in intel_pmu_refresh(), i.e. give userspace full control over capability/read-only MSRs. KVM is not a babysitter, it is userspace's responsiblity to provide a valid and coherent vCPU model. Attempting to "help" the guest by forcing a consistent model creates edge cases, and ironicially leads to inconsistent behavior. Example #1: KVM doesn't do intel_pmu_refresh() when userspace writes the MSR. Example #2: KVM doesn't clear the bits when the PMU is disabled, or when there's no architectural PMU. Signed-off-by:
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Sean Christopherson authored
Give userspace full control of the read-only bits in MISC_ENABLES, i.e. do not modify bits on PMU refresh and do not preserve existing bits when userspace writes MISC_ENABLES. With a few exceptions where KVM doesn't expose the necessary controls to userspace _and_ there is a clear cut association with CPUID, e.g. reserved CR4 bits, KVM does not own the vCPU and should not manipulate the vCPU model on behalf of "dummy user space". The argument that KVM is doing userspace a favor because "the order of setting vPMU capabilities and MSR_IA32_MISC_ENABLE is not strictly guaranteed" is specious, as attempting to configure MSRs on behalf of userspace inevitably leads to edge cases precisely because KVM does not prescribe a specific order of initialization. Example #1: intel_pmu_refresh() consumes and modifies the vCPU's MSR_IA32_PERF_CAPABILITIES, and so assumes userspace initializes config MSRs before setting the guest CPUID model. If userspace sets CPUID first, then KVM will mark PEBS as available when arch.perf_capabilities is initialized with a non-zero PEBS format, thus creating a bad vCPU model if userspace later disables PEBS by writing PERF_CAPABILITIES. Example #2: intel_pmu_refresh() does not clear PERF_CAP_PEBS_MASK in MSR_IA32_PERF_CAPABILITIES if there is no vPMU, making KVM inconsistent in its desire to be consistent. Example #3: intel_pmu_refresh() does not clear MSR_IA32_MISC_ENABLE_EMON if KVM_SET_CPUID2 is called multiple times, first with a vPMU, then without a vPMU. While slightly contrived, it's plausible a VMM could reflect KVM's default vCPU and then operate on KVM's copy of CPUID to later clear the vPMU settings, e.g. see KVM's selftests. Example #4: Enumerating an Intel vCPU on an AMD host will not call into intel_pmu_refresh() at any point, and so the BTS and PEBS "unavailable" bits will be left clear, without any way for userspace to set them. Keep the "R" behavior of the bit 7, "EMON available", for the guest. Unlike the BTS and PEBS bits, which are fully "RO", the EMON bit can be written with a different value, but that new value is ignored. Cc: Like Xu <likexu@tencent.com> Signed-off-by:
kernel test robot <oliver.sang@intel.com> Message-Id: <20220611005755.753273-2-seanjc@google.com> Signed-off-by:
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Dongliang Mu authored
kfree can handle NULL pointer as its argument. According to coccinelle isnullfree check, remove NULL check before kfree operation. Signed-off-by:
Dongliang Mu <mudongliangabcd@gmail.com> Message-Id: <20220614133458.147314-1-dzm91@hust.edu.cn> Signed-off-by:
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Sean Christopherson authored
Drop the unnecessary initialization of the local 'pfn' variable in hva_to_pfn(). First and foremost, '0' is not an invalid pfn, it's a perfectly valid pfn on most architectures. I.e. if hva_to_pfn() were to return an "uninitializd" pfn, it would actually be interpeted as a legal pfn by most callers. Second, hva_to_pfn() can't return an uninitialized pfn as hva_to_pfn() explicitly sets pfn to an error value (or returns an error value directly) if a helper returns failure, and all helpers set the pfn on success. The zeroing of 'pfn' was introduced by commit 2fc84311 ("KVM: reorganize hva_to_pfn"), probably to avoid "uninitialized variable" warnings on statements that return pfn. However, no compiler seems to produce them, making the initialization unnecessary. Signed-off-by:
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Sean Christopherson authored
Move the check that restricts mapping huge pages into the guest to pfns that are backed by refcounted 'struct page' memory into the helper that actually "requires" a 'struct page', host_pfn_mapping_level(). In addition to deduplicating code, moving the check to the helper eliminates the subtle requirement that the caller check that the incoming pfn is backed by a refcounted struct page, and as an added bonus avoids an extra pfn_to_page() lookup. Note, the is_error_noslot_pfn() check in kvm_mmu_hugepage_adjust() needs to stay where it is, as it guards against dereferencing a NULL memslot in the kvm_slot_dirty_track_enabled() that follows. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Rename and refactor kvm_is_reserved_pfn() to kvm_pfn_to_refcounted_page() to better reflect what KVM is actually checking, and to eliminate extra pfn_to_page() lookups. The kvm_release_pfn_*() an kvm_try_get_pfn() helpers in particular benefit from "refouncted" nomenclature, as it's not all that obvious why KVM needs to get/put refcounts for some PG_reserved pages (ZERO_PAGE and ZONE_DEVICE). Add a comment to call out that the list of exceptions to PG_reserved is all but guaranteed to be incomplete. The list has mostly been compiled by people throwing noodles at KVM and finding out they stick a little too well, e.g. the ZERO_PAGE's refcount overflowed and ZONE_DEVICE pages didn't get freed. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Operate on a 'struct page' instead of a pfn when checking if a page is a ZONE_DEVICE page, and rename the helper accordingly. Generally speaking, KVM doesn't actually care about ZONE_DEVICE memory, i.e. shouldn't do anything special for ZONE_DEVICE memory. Rather, KVM wants to treat ZONE_DEVICE memory like regular memory, and the need to identify ZONE_DEVICE memory only arises as an exception to PG_reserved pages. In other words, KVM should only ever check for ZONE_DEVICE memory after KVM has already verified that there is a struct page associated with the pfn. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Drop helpers to convert a gfn/gpa to a 'struct page' in the context of a vCPU. KVM doesn't require that guests be backed by 'struct page' memory, thus any use of helpers that assume 'struct page' is bound to be flawed, as was the case for the recently removed last user in x86's nested VMX. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Drop a WARN_ON() if kvm_pfn_to_page() encounters a "reserved" pfn, which in this context means a struct page that has PG_reserved but is not a/the ZERO_PAGE and is not a ZONE_DEVICE page. The usage, via gfn_to_page(), in x86 is safe as gfn_to_page() is used only to retrieve a page from KVM-controlled memslot, but the usage in PPC and s390 operates on arbitrary gfns and thus memslots that can be backed by incompatible memory. Signed-off-by:
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Sean Christopherson authored
Use kvm_vcpu_map() to get/pin the backing for vmcs12's APIC-access page, there's no reason it has to be restricted to 'struct page' backing. The APIC-access page actually doesn't need to be backed by anything, which is ironically why it got left behind by the series which introduced kvm_vcpu_map()[1]; the plan was to shove a dummy pfn into vmcs02[2], but that code never got merged. Switching the APIC-access page to kvm_vcpu_map() doesn't preclude using a magic pfn in the future, and will allow a future patch to drop kvm_vcpu_gpa_to_page(). [1] https://lore.kernel.org/all/1547026933-31226-1-git-send-email-karahmed@amazon.de [2] https://lore.kernel.org/lkml/1543845551-4403-1-git-send-email-karahmed@amazon.deSigned-off-by:
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Sean Christopherson authored
Invert the order of KVM's page/pfn release helpers so that the "inner" helper operates on a page instead of a pfn. As pointed out by Linus[*], converting between struct page and a pfn isn't necessarily cheap, and that's not even counting the overhead of is_error_noslot_pfn() and kvm_is_reserved_pfn(). Even if the checks were dirt cheap, there's no reason to convert from a page to a pfn and back to a page, just to mark the page dirty/accessed or to put a reference to the page. Opportunistically drop a stale declaration of kvm_set_page_accessed() from kvm_host.h (there was no implementation). No functional change intended. [*] https://lore.kernel.org/all/CAHk-=wifQimj2d6npq-wCi5onYPjzQg4vyO4tFcPJJZr268cRw@mail.gmail.comSigned-off-by:
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Sean Christopherson authored
Don't set Accessed/Dirty bits for a struct page with PG_reserved set, i.e. don't set A/D bits for the ZERO_PAGE. The ZERO_PAGE (or pages depending on the architecture) should obviously never be written, and similarly there's no point in marking it accessed as the page will never be swapped out or reclaimed. The comment in page-flags.h is quite clear that PG_reserved pages should be managed only by their owner, and strictly following that mandate also simplifies KVM's logic. Fixes: 7df003c8 ("KVM: fix overflow of zero page refcount with ksm running") Signed-off-by:
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Sean Christopherson authored
Remove a check from kvm_release_pfn() to bail if the provided @pfn is zero. Zero is a perfectly valid pfn on most architectures, and should not be used to indicate an error or an invalid pfn. The bogus check was added by commit 91724814 ("x86/kvm: Cache gfn to pfn translation"), which also did the bad thing of zeroing the pfn and gfn to mark a cache invalid. Thankfully, that bad behavior was axed by commit 357a18ad ("KVM: Kill kvm_map_gfn() / kvm_unmap_gfn() and gfn_to_pfn_cache"). Signed-off-by:
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