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authorJeremi Piotrowski <jpiotrowski@linux.microsoft.com>2023-03-24 17:52:33 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2023-03-27 17:10:26 +0300
commite5c972c1fadacc858b6a564d056f177275238040 (patch)
tree4868407726dc3b649faa2073b5dbf8945e3be155 /virt
parent9e347ba03029e10e6405f8c3a7a91a5597943ed9 (diff)
downloadlinux-e5c972c1fadacc858b6a564d056f177275238040.tar.xz
KVM: SVM: Flush Hyper-V TLB when required
The Hyper-V "EnlightenedNptTlb" enlightenment is always enabled when KVM is running on top of Hyper-V and Hyper-V exposes support for it (which is always). On AMD CPUs this enlightenment results in ASID invalidations not flushing TLB entries derived from the NPT. To force the underlying (L0) hypervisor to rebuild its shadow page tables, an explicit hypercall is needed. The original KVM implementation of Hyper-V's "EnlightenedNptTlb" on SVM only added remote TLB flush hooks. This worked out fine for a while, as sufficient remote TLB flushes where being issued in KVM to mask the problem. Since v5.17, changes in the TDP code reduced the number of flushes and the out-of-sync TLB prevents guests from booting successfully. Split svm_flush_tlb_current() into separate callbacks for the 3 cases (guest/all/current), and issue the required Hyper-V hypercall when a Hyper-V TLB flush is needed. The most important case where the TLB flush was missing is when loading a new PGD, which is followed by what is now svm_flush_tlb_current(). Cc: stable@vger.kernel.org # v5.17+ Fixes: 1e0c7d40758b ("KVM: SVM: hyper-v: Remote TLB flush for SVM") Link: https://lore.kernel.org/lkml/43980946-7bbf-dcef-7e40-af904c456250@linux.microsoft.com/ Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20230324145233.4585-1-jpiotrowski@linux.microsoft.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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