On 2021/11/26 21:21, Paolo Bonzini wrote:
Initialize the mask for PKU permissions as if CR4.PKE=0, avoiding incorrect interpretations of the nested hypervisor's page tables.
I think the AMD64 volume2 Architecture Programmer’s Manual does not specify it, but it seems that for a sane NPT walk, PKU should not work in NPT.
I once planed to set cr0 = X86_CR0_PG | X86_CR0_WP; cr4 = cr4 & ~(X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_PKE);
It adds X86_CR0_WP and removes smep smap just because it is always usermode access, and it has no meaning for CR0_WP, smep, smap. Setting it like this ways can reduce the role combination.
Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com
arch/x86/kvm/mmu/mmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 5942e9c6dd6e..a33b5361bc67 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4855,7 +4855,7 @@ void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0, struct kvm_mmu *context = &vcpu->arch.guest_mmu; struct kvm_mmu_role_regs regs = { .cr0 = cr0,
.cr4 = cr4,
.cr4 = cr4 & ~X86_CR4_PKE,@@ -4919,7 +4919,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly, context->direct_map = false; update_permission_bitmask(context, true);
- update_pkru_bitmask(context);
- context->pkru_mask = 0;
It is not worth to optimize it since update_pkru_bitmask() will also just set context->pkru_mask = 0 and then return.
reset_rsvds_bits_mask_ept(vcpu, context, execonly); reset_ept_shadow_zero_bits_mask(vcpu, context, execonly); }