2023-08-03 07:40:18

by Yang Weijiang

Subject: [PATCH v5 07/19] KVM:x86: Add fault checks for guest CR4.CET setting

Check potential faults for CR4.CET setting per Intel SDM.
CET can be enabled if and only if CR0.WP==1, i.e. setting
CR4.CET=1 faults if CR0.WP==0 and setting CR0.WP=0 fails
if CR4.CET==1.

Co-developed-by: Sean Christopherson <[email protected]>
Signed-off-by: Sean Christopherson <[email protected]>
Signed-off-by: Yang Weijiang <[email protected]>
---
arch/x86/kvm/x86.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 015fb0ef102c..82b9f14990da 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -993,6 +993,9 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
(is_64_bit_mode(vcpu) || kvm_is_cr4_bit_set(vcpu, X86_CR4_PCIDE)))
return 1;

+ if (!(cr0 & X86_CR0_WP) && kvm_is_cr4_bit_set(vcpu, X86_CR4_CET))
+ return 1;
+
static_call(kvm_x86_set_cr0)(vcpu, cr0);

kvm_post_set_cr0(vcpu, old_cr0, cr0);
@@ -1204,6 +1207,9 @@ int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
return 1;
}

+ if ((cr4 & X86_CR4_CET) && !kvm_is_cr0_bit_set(vcpu, X86_CR0_WP))
+ return 1;
+
static_call(kvm_x86_set_cr4)(vcpu, cr4);

kvm_post_set_cr4(vcpu, old_cr4, cr4);
--
2.27.0

2023-08-03 11:52:50

by Chao Gao

Subject: Re: [PATCH v5 07/19] KVM:x86: Add fault checks for guest CR4.CET setting

nit: add a space betwen "KVM:" and "x86:" in the short changelog.

On Thu, Aug 03, 2023 at 12:27:20AM -0400, Yang Weijiang wrote:
>Check potential faults for CR4.CET setting per Intel SDM.
>CET can be enabled if and only if CR0.WP==1, i.e. setting
>CR4.CET=1 faults if CR0.WP==0 and setting CR0.WP=0 fails
>if CR4.CET==1.
>
>Co-developed-by: Sean Christopherson <[email protected]>
>Signed-off-by: Sean Christopherson <[email protected]>
>Signed-off-by: Yang Weijiang <[email protected]>

Reviewed-by: Chao Gao <[email protected]>