On 02/03/21 13:56, Cathy Avery wrote:
On 3/1/21 7:59 PM, Sean Christopherson wrote:
On Mon, Mar 01, 2021, Cathy Avery wrote:
svm->nested.vmcb12_gpa = 0;
+ svm->nested.last_vmcb12_gpa = 0;
This should not be 0 to avoid a false match. "-1" should be okay.
kvm_set_rflags(&svm->vcpu, vmcb12->save.rflags |
X86_EFLAGS_FIXED);
svm_set_efer(&svm->vcpu, vmcb12->save.efer);
svm_set_cr0(&svm->vcpu, vmcb12->save.cr0);
svm_set_cr4(&svm->vcpu, vmcb12->save.cr4);
Why not utilize VMCB_CR?
I was going to tackle CR in a follow up patch. I should have mentioned
that but it makes sense to go ahead and do it now.
There is some trickiness. For example, I would first prefer to move the
checks on svm->vmcb->save.cr0 == vcpu->arch.cr0 ("hcr0 == cr0" in
svm_set_cr0) to recalc_intercepts.
For cr4, instead, we need to go through kvm_update_cpuid_runtime in case
host CR4 is not equal to CR4 (for which we have a testcase in svm.flat
already, I think).
- svm->vcpu.arch.cr2 = vmcb12->save.cr2;
+ svm->vmcb->save.cr2 = svm->vcpu.arch.cr2 = vmcb12->save.cr2;
Same question for VMCB_CR2.
Also, isn't writing svm->vmcb->save.cr2 unnecessary since svm_vcpu_run()
unconditionally writes it?
Alternatively, it shouldn't be too much work to add proper dirty
tracking for CR2. VMX has to write the real CR2 every time because there's no VMCS
field, but I assume can avoid the write and dirty update on the majority of
VMRUNs.
I'll take a look at CR2 as well.
That's a separate patch, to some extent unrelated to nesting. Feel free
to look at it, but for now we should apply this part with only the
svm->vmcb->save.cr2 assignment removed. Please send a v2, thanks!
Paolo
Thanks for the feedback,
Cathy
+
kvm_rax_write(&svm->vcpu, vmcb12->save.rax);
kvm_rsp_write(&svm->vcpu, vmcb12->save.rsp);
kvm_rip_write(&svm->vcpu, vmcb12->save.rip);
/* In case we don't even reach vcpu_run, the fields are not
updated */
- svm->vmcb->save.cr2 = svm->vcpu.arch.cr2;
svm->vmcb->save.rax = vmcb12->save.rax;
svm->vmcb->save.rsp = vmcb12->save.rsp;
svm->vmcb->save.rip = vmcb12->save.rip;
- svm->vmcb->save.dr7 = vmcb12->save.dr7 | DR7_FIXED_1;
- svm->vcpu.arch.dr6 = vmcb12->save.dr6 | DR6_ACTIVE_LOW;
- vmcb_mark_dirty(svm->vmcb, VMCB_DR);
+ /* These bits will be set properly on the first execution when
new_vmc12 is true */
+ if (unlikely(new_vmcb12 || vmcb_is_dirty(vmcb12, VMCB_DR))) {
+ svm->vmcb->save.dr7 = vmcb12->save.dr7 | DR7_FIXED_1;
+ svm->vcpu.arch.dr6 = vmcb12->save.dr6 | DR6_ACTIVE_LOW;
+ vmcb_mark_dirty(svm->vmcb, VMCB_DR);
+ }
}
static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 54610270f66a..9761a7ca8100 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1232,6 +1232,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
svm->asid = 0;
svm->nested.vmcb12_gpa = 0;
+ svm->nested.last_vmcb12_gpa = 0;
We should use INVALID_PAGE, '0' is a legal physical address and could
theoretically get a false negative on the "new_vmcb12" check.
vcpu->arch.hflags = 0;
if (!kvm_pause_in_guest(vcpu->kvm)) {
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index fbbb26dd0f73..911868d4584c 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -93,6 +93,7 @@ struct svm_nested_state {
u64 hsave_msr;
u64 vm_cr_msr;
u64 vmcb12_gpa;
+ u64 last_vmcb12_gpa;
/* These are the merged vectors */
u32 *msrpm;
@@ -247,6 +248,11 @@ static inline void vmcb_mark_dirty(struct vmcb
*vmcb, int bit)
vmcb->control.clean &= ~(1 << bit);
}
+static inline bool vmcb_is_dirty(struct vmcb *vmcb, int bit)
+{
+ return !test_bit(bit, (unsigned long *)&vmcb->control.clean);
+}
+
static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
{
return container_of(vcpu, struct vcpu_svm, vcpu);
--
2.26.2
