From: Sean Christopherson seanjc@google.com
stable inclusion from stable-5.10.48 commit 4dc96804286498f74beabcfb7603bb76d9905ad9 bugzilla: 173268 https://gitee.com/openeuler/kernel/issues/I4DD1K
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit f71a53d1180d5ecc346f0c6a23191d837fe2871b upstream.
Restore CR4.LA57 to the mmu_role to fix an amusing edge case with nested virtualization. When KVM (L0) is using TDP, CR4.LA57 is not reflected in mmu_role.base.level because that tracks the shadow root level, i.e. TDP level. Normally, this is not an issue because LA57 can't be toggled while long mode is active, i.e. the guest has to first disable paging, then toggle LA57, then re-enable paging, thus ensuring an MMU reinitialization.
But if L1 is crafty, it can load a new CR4 on VM-Exit and toggle LA57 without having to bounce through an unpaged section. L1 can also load a new CR3 on exit, i.e. it doesn't even need to play crazy paging games, a single entry PML5 is sufficient. Such shenanigans are only problematic if L0 and L1 use TDP, otherwise L1 and L2 share an MMU that gets reinitialized on nested VM-Enter/VM-Exit due to mmu_role.base.guest_mode.
Note, in the L2 case with nested TDP, even though L1 can switch between L2s with different LA57 settings, thus bypassing the paging requirement, in that case KVM's nested_mmu will track LA57 in base.level.
This reverts commit 8053f924cad30bf9f9a24e02b6c8ddfabf5202ea.
Fixes: 8053f924cad3 ("KVM: x86/mmu: Drop kvm_mmu_extended_role.cr4_la57 hack") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20210622175739.3610207-6-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
Signed-off-by: Chen Jun chenjun102@huawei.com Acked-by: Weilong Chen chenweilong@huawei.com Signed-off-by: Chen Jun chenjun102@huawei.com --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu/mmu.c | 1 + 2 files changed, 2 insertions(+)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 90c34de3fefc..d715ce29bfc3 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -296,6 +296,7 @@ union kvm_mmu_extended_role { unsigned int cr4_pke:1; unsigned int cr4_smap:1; unsigned int cr4_smep:1; + unsigned int cr4_la57:1; unsigned int maxphyaddr:6; }; }; diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 6b794344c02d..f2eeaf197294 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4442,6 +4442,7 @@ static union kvm_mmu_extended_role kvm_calc_mmu_role_ext(struct kvm_vcpu *vcpu) ext.cr4_smap = !!kvm_read_cr4_bits(vcpu, X86_CR4_SMAP); ext.cr4_pse = !!is_pse(vcpu); ext.cr4_pke = !!kvm_read_cr4_bits(vcpu, X86_CR4_PKE); + ext.cr4_la57 = !!kvm_read_cr4_bits(vcpu, X86_CR4_LA57); ext.maxphyaddr = cpuid_maxphyaddr(vcpu);
ext.valid = 1;