lkml.org 
[lkml]   [2020]   [Mar]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v11 4/9] KVM: VMX: Check CET dependencies on CR settings
Date
CR4.CET is master control bit for CET function.
There're mutual constrains between CR0.WP and CR4.CET, so need
to check the dependent bit while changing the control registers.

Note:
1)The processor does not allow CR4.CET to be set if CR0.WP = 0,
similarly, it does not allow CR0.WP to be cleared while
CR4.CET = 1. In either case, KVM would inject #GP to guest.

2)SHSTK and IBT features share one control MSR:
MSR_IA32_{U,S}_CET, which means it's difficult to hide
one feature from another in the case of SHSTK != IBT,
after discussed in community, it's agreed to allow guest
control two features independently as it won't introduce
security hole.

Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
arch/x86/kvm/vmx/vmx.c | 4 ++++
arch/x86/kvm/x86.c | 3 +++
2 files changed, 7 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index bd7cd175fd81..87f101750746 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3089,6 +3089,10 @@ int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
return 1;
}

+ if ((cr4 & X86_CR4_CET) && (!is_cet_supported(vcpu) ||
+ !(kvm_read_cr0(vcpu) & X86_CR0_WP)))
+ return 1;
+
if (vmx->nested.vmxon && !nested_cr4_valid(vcpu, cr4))
return 1;

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 830afe5038d1..90acdbbb8a5a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -804,6 +804,9 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
if (!(cr0 & X86_CR0_PG) && kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE))
return 1;

+ if (!(cr0 & X86_CR0_WP) && kvm_read_cr4_bits(vcpu, X86_CR4_CET))
+ return 1;
+
kvm_x86_ops->set_cr0(vcpu, cr0);

if ((cr0 ^ old_cr0) & X86_CR0_PG) {
--
2.17.2
\
 
 \ /
  Last update: 2020-03-26 09:17    [W:0.085 / U:0.868 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site