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| author | Mathias Krause <minipli@grsecurity.net> | 2023-05-08 17:46:01 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-17 11:53:29 +0200 |
| commit | 71e848bac0a4daaae2bd980a8cb2b0b4c7ef3a9d (patch) | |
| tree | 55f520e0414e2044b014d58812d4b39f55a4305a /arch/x86/kvm/vmx/nested.c | |
| parent | 27ec4cbc1d51cfc7238c398c546b38517dcaeb18 (diff) | |
| download | linux-71e848bac0a4daaae2bd980a8cb2b0b4c7ef3a9d.tar.gz | |
KVM: VMX: Make CR0.WP a guest owned bit
[ Upstream commit fb509f76acc8d42bed11bca308404f81c2be856a ] Guests like grsecurity that make heavy use of CR0.WP to implement kernel level W^X will suffer from the implied VMEXITs. With EPT there is no need to intercept a guest change of CR0.WP, so simply make it a guest owned bit if we can do so. This implies that a read of a guest's CR0.WP bit might need a VMREAD. However, the only potentially affected user seems to be kvm_init_mmu() which is a heavy operation to begin with. But also most callers already cache the full value of CR0 anyway, so no additional VMREAD is needed. The only exception is nested_vmx_load_cr3(). This change is VMX-specific, as SVM has no such fine grained control register intercept control. Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Mathias Krause <minipli@grsecurity.net> Link: https://lore.kernel.org/r/20230322013731.102955-7-minipli@grsecurity.net Co-developed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Mathias Krause <minipli@grsecurity.net> # backport to v6.1.x Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/x86/kvm/vmx/nested.c')
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 8e56ec6e72e9..9d683b6067c7 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -4460,7 +4460,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu, * CR0_GUEST_HOST_MASK is already set in the original vmcs01 * (KVM doesn't change it); */ - vcpu->arch.cr0_guest_owned_bits = KVM_POSSIBLE_CR0_GUEST_BITS; + vcpu->arch.cr0_guest_owned_bits = vmx_l1_guest_owned_cr0_bits(); vmx_set_cr0(vcpu, vmcs12->host_cr0); /* Same as above - no reason to call set_cr4_guest_host_mask(). */ @@ -4611,7 +4611,7 @@ static void nested_vmx_restore_host_state(struct kvm_vcpu *vcpu) */ vmx_set_efer(vcpu, nested_vmx_get_vmcs01_guest_efer(vmx)); - vcpu->arch.cr0_guest_owned_bits = KVM_POSSIBLE_CR0_GUEST_BITS; + vcpu->arch.cr0_guest_owned_bits = vmx_l1_guest_owned_cr0_bits(); vmx_set_cr0(vcpu, vmcs_readl(CR0_READ_SHADOW)); vcpu->arch.cr4_guest_owned_bits = ~vmcs_readl(CR4_GUEST_HOST_MASK); |