2020-05-29 15:44:53

by Paolo Bonzini

[permalink] [raw]
Subject: [PATCH 10/30] KVM: nSVM: extract preparation of VMCB for nested run

Split out filling svm->vmcb.save and svm->vmcb.control before VMRUN.
Only the latter will be useful when restoring nested SVM state.

This patch introduces no semantic change, so the MMU setup is still
done in nested_prepare_vmcb_save. The next patch will clean up things.

Signed-off-by: Paolo Bonzini <[email protected]>
---
arch/x86/kvm/svm/nested.c | 40 +++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index fc0c6d1678eb..73be7af79453 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -245,21 +245,8 @@ static void load_nested_vmcb_control(struct vcpu_svm *svm,
svm->vcpu.arch.tsc_offset += control->tsc_offset;
}

-void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
- struct vmcb *nested_vmcb)
+static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_vmcb)
{
- bool evaluate_pending_interrupts =
- is_intercept(svm, INTERCEPT_VINTR) ||
- is_intercept(svm, INTERCEPT_IRET);
-
- svm->nested.vmcb = vmcb_gpa;
- if (kvm_get_rflags(&svm->vcpu) & X86_EFLAGS_IF)
- svm->vcpu.arch.hflags |= HF_HIF_MASK;
- else
- svm->vcpu.arch.hflags &= ~HF_HIF_MASK;
-
- load_nested_vmcb_control(svm, &nested_vmcb->control);
-
if (nested_vmcb->control.nested_ctl & SVM_NESTED_CTL_NP_ENABLE)
nested_svm_init_mmu_context(&svm->vcpu);

@@ -291,7 +278,10 @@ void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
svm->vmcb->save.dr7 = nested_vmcb->save.dr7;
svm->vcpu.arch.dr6 = nested_vmcb->save.dr6;
svm->vmcb->save.cpl = nested_vmcb->save.cpl;
+}

+static void nested_prepare_vmcb_control(struct vcpu_svm *svm, struct vmcb *nested_vmcb)
+{
svm_flush_tlb(&svm->vcpu);
if (nested_vmcb->control.int_ctl & V_INTR_MASKING_MASK)
svm->vcpu.arch.hflags |= HF_VINTR_MASK;
@@ -321,6 +311,26 @@ void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
*/
recalc_intercepts(svm);

+ mark_all_dirty(svm->vmcb);
+}
+
+void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
+ struct vmcb *nested_vmcb)
+{
+ bool evaluate_pending_interrupts =
+ is_intercept(svm, INTERCEPT_VINTR) ||
+ is_intercept(svm, INTERCEPT_IRET);
+
+ svm->nested.vmcb = vmcb_gpa;
+ if (kvm_get_rflags(&svm->vcpu) & X86_EFLAGS_IF)
+ svm->vcpu.arch.hflags |= HF_HIF_MASK;
+ else
+ svm->vcpu.arch.hflags &= ~HF_HIF_MASK;
+
+ load_nested_vmcb_control(svm, &nested_vmcb->control);
+ nested_prepare_vmcb_save(svm, nested_vmcb);
+ nested_prepare_vmcb_control(svm, nested_vmcb);
+
/*
* If L1 had a pending IRQ/NMI before executing VMRUN,
* which wasn't delivered because it was disallowed (e.g.
@@ -336,8 +346,6 @@ void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
enable_gif(svm);
if (unlikely(evaluate_pending_interrupts))
kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
-
- mark_all_dirty(svm->vmcb);
}

int nested_svm_vmrun(struct vcpu_svm *svm)
--
2.26.2



2020-05-29 18:32:11

by Krish Sadhukhan

[permalink] [raw]
Subject: Re: [PATCH 10/30] KVM: nSVM: extract preparation of VMCB for nested run


On 5/29/20 8:39 AM, Paolo Bonzini wrote:
> Split out filling svm->vmcb.save and svm->vmcb.control before VMRUN.
> Only the latter will be useful when restoring nested SVM state.
>
> This patch introduces no semantic change, so the MMU setup is still
> done in nested_prepare_vmcb_save. The next patch will clean up things.
>
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> arch/x86/kvm/svm/nested.c | 40 +++++++++++++++++++++++----------------
> 1 file changed, 24 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index fc0c6d1678eb..73be7af79453 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -245,21 +245,8 @@ static void load_nested_vmcb_control(struct vcpu_svm *svm,
> svm->vcpu.arch.tsc_offset += control->tsc_offset;
> }
>
> -void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
> - struct vmcb *nested_vmcb)
> +static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_vmcb)


Not a big deal, but I feel that it helps a lot in readability if we keep
the names symmetric. This one could be named prepare_nested_vmcb_save to
match load_nested_vmcb_control that you created in the previous patch.
Or load_nested_vmcb_control could be renamed to nested_load_vmcb_control
to match the name here.

> {
> - bool evaluate_pending_interrupts =
> - is_intercept(svm, INTERCEPT_VINTR) ||
> - is_intercept(svm, INTERCEPT_IRET);
> -
> - svm->nested.vmcb = vmcb_gpa;
> - if (kvm_get_rflags(&svm->vcpu) & X86_EFLAGS_IF)
> - svm->vcpu.arch.hflags |= HF_HIF_MASK;
> - else
> - svm->vcpu.arch.hflags &= ~HF_HIF_MASK;
> -
> - load_nested_vmcb_control(svm, &nested_vmcb->control);
> -
> if (nested_vmcb->control.nested_ctl & SVM_NESTED_CTL_NP_ENABLE)
> nested_svm_init_mmu_context(&svm->vcpu);
>
> @@ -291,7 +278,10 @@ void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
> svm->vmcb->save.dr7 = nested_vmcb->save.dr7;
> svm->vcpu.arch.dr6 = nested_vmcb->save.dr6;
> svm->vmcb->save.cpl = nested_vmcb->save.cpl;
> +}
>
> +static void nested_prepare_vmcb_control(struct vcpu_svm *svm, struct vmcb *nested_vmcb)
> +{
> svm_flush_tlb(&svm->vcpu);
> if (nested_vmcb->control.int_ctl & V_INTR_MASKING_MASK)
> svm->vcpu.arch.hflags |= HF_VINTR_MASK;
> @@ -321,6 +311,26 @@ void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
> */
> recalc_intercepts(svm);
>
> + mark_all_dirty(svm->vmcb);
> +}
> +
> +void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
> + struct vmcb *nested_vmcb)
> +{
> + bool evaluate_pending_interrupts =
> + is_intercept(svm, INTERCEPT_VINTR) ||
> + is_intercept(svm, INTERCEPT_IRET);
> +
> + svm->nested.vmcb = vmcb_gpa;
> + if (kvm_get_rflags(&svm->vcpu) & X86_EFLAGS_IF)
> + svm->vcpu.arch.hflags |= HF_HIF_MASK;
> + else
> + svm->vcpu.arch.hflags &= ~HF_HIF_MASK;
> +
> + load_nested_vmcb_control(svm, &nested_vmcb->control);
> + nested_prepare_vmcb_save(svm, nested_vmcb);
> + nested_prepare_vmcb_control(svm, nested_vmcb);
> +
> /*
> * If L1 had a pending IRQ/NMI before executing VMRUN,
> * which wasn't delivered because it was disallowed (e.g.
> @@ -336,8 +346,6 @@ void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
> enable_gif(svm);
> if (unlikely(evaluate_pending_interrupts))
> kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
> -
> - mark_all_dirty(svm->vmcb);
> }
>
> int nested_svm_vmrun(struct vcpu_svm *svm)

2020-05-29 19:06:39

by Paolo Bonzini

[permalink] [raw]
Subject: Re: [PATCH 10/30] KVM: nSVM: extract preparation of VMCB for nested run

On 29/05/20 20:27, Krish Sadhukhan wrote:
>>
>> +static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct
>> vmcb *nested_vmcb)
>
>
> Not a big deal, but I feel that it helps a lot in readability if we keep
> the names symmetric. This one could be named prepare_nested_vmcb_save to
> match load_nested_vmcb_control that you created in the previous patch.
> Or load_nested_vmcb_control could be renamed to nested_load_vmcb_control
> to match the name here.

This is actually intended: while load_nested_vmcb_control loads the
members of nested_vmcb->control into svm->nested, the two functions in
this patch prepare the svm->vmcb. A couple patches later,
nested_prepare_vmcb_control will not use nested_vmcb anymore.

I could use nested_load_nested_vmcb_control, but that is just too ugly!
Instead, the best thing to do would be to use the vmcb01/vmcb02/vmcb12
names as in nVMX, in which case the functions would become
nested_load_vmcb12_control and nested_prepare_vmcb02_{save,control}.
However this is a bit hard to do right now because the svm->vmcb acts as
both vmcb01 and vmcb02 depending on what is running.

Thanks,

Paolo