korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-14 15:54:15 +08:00
Code Issues Packages Projects Releases Wiki Activity

KVM: VMX: Pull GUEST_CR3 from the VMCS iff CR3 load exiting is disabled

Browse Source 
Tweak the logic for grabbing vmcs.GUEST_CR3 in vmx_cache_reg() to look
directly at the execution controls, as opposed to effectively inferring
the controls based on vCPUs.  Inferring the controls isn't wrong, but it
creates a very subtle dependency between the caching logic, the state of
vcpu->arch.cr0 (via is_paging()), and the behavior of vmx_set_cr0().

Using the execution controls doesn't completely eliminate the dependency
in vmx_set_cr0(), e.g. neglecting to cache CR3 before enabling
interception would still break the guest, but it does reduce the
code dependency and mostly eliminate the logical dependency (that CR3
loads are intercepted in certain scenarios).  Eliminating the subtle
read of vcpu->arch.cr0 will also allow for additional cleanup in
vmx_set_cr0().

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-26-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-07-13 09:33:03 -07:00 committed by Paolo Bonzini
parent 470750b342
commit 81ca0e7340
1 changed files with 5 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/x86/kvm/vmx/vmx.c
View File

@ -2262,8 +2262,11 @@ static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
vcpu->arch.cr0 |= vmcs_readl(GUEST_CR0) & guest_owned_bits;
break;
case VCPU_EXREG_CR3:
if (is_unrestricted_guest(vcpu) ||
(enable_ept && is_paging(vcpu)))
/*
* When intercepting CR3 loads, e.g. for shadowing paging, KVM's
* CR3 is loaded into hardware, not the guest's CR3.
*/
if (!(exec_controls_get(to_vmx(vcpu)) & CPU_BASED_CR3_LOAD_EXITING))
vcpu->arch.cr3 = vmcs_readl(GUEST_CR3);
break;
case VCPU_EXREG_CR4: