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| author | Brijesh Singh <brijesh.singh@amd.com> | 2017-08-07 14:11:30 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-09-13 14:20:53 -0700 |
| commit | 9d7960e036cc72f46fbd2bec82aacf57382d53d0 (patch) | |
| tree | d8281a924e54f1863d04f68a111ef53b0a3291b7 /drivers/base/firmware_class.c | |
| parent | 21d9f614bda72f3df578dda4d895135b413fcca3 (diff) | |
KVM: SVM: Limit PFERR_NESTED_GUEST_PAGE error_code check to L1 guest
commit 64531a3b70b17c8d3e77f2e49e5e1bb70f571266 upstream.
Commit 147277540bbc ("kvm: svm: Add support for additional SVM NPF error
codes", 2016-11-23) added a new error code to aid nested page fault
handling. The commit unprotects (kvm_mmu_unprotect_page) the page when
we get a NPF due to guest page table walk where the page was marked RO.
However, if an L0->L2 shadow nested page table can also be marked read-only
when a page is read only in L1's nested page table. If such a page
is accessed by L2 while walking page tables it can cause a nested
page fault (page table walks are write accesses). However, after
kvm_mmu_unprotect_page we may get another page fault, and again in an
endless stream.
To cover this use case, we qualify the new error_code check with
vcpu->arch.mmu_direct_map so that the error_code check would run on L1
guest, and not the L2 guest. This avoids hitting the above scenario.
Fixes: 147277540bbc54119172481c8ef6d930cc9fbfc2
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/base/firmware_class.c')
0 files changed, 0 insertions, 0 deletions