2019-08-15 20:56:34

by Sean Christopherson

Subject: [PATCH] KVM: VMX: Fix and tweak the comments for VM-Enter

Fix an incorrect/stale comment regarding the vmx_vcpu pointer, as guest
registers are now loaded using a direct pointer to the start of the
register array.

Opportunistically add a comment to document why the vmx_vcpu pointer is
needed, its consumption via 'call vmx_update_host_rsp' is rather subtle.

Signed-off-by: Sean Christopherson <[email protected]>
---
arch/x86/kvm/vmx/vmenter.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S
index 4010d519eb8c..751a384c2eb0 100644
--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -94,7 +94,7 @@ ENDPROC(vmx_vmexit)

/**
* __vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode
- * @vmx: struct vcpu_vmx *
+ * @vmx: struct vcpu_vmx * (forwarded to vmx_update_host_rsp)
* @regs: unsigned long * (to guest registers)
* @launched: %true if the VMCS has been launched
*
@@ -151,7 +151,7 @@ ENTRY(__vmx_vcpu_run)
mov VCPU_R14(%_ASM_AX), %r14
mov VCPU_R15(%_ASM_AX), %r15
#endif
- /* Load guest RAX. This kills the vmx_vcpu pointer! */
+ /* Load guest RAX. This kills the @regs pointer! */
mov VCPU_RAX(%_ASM_AX), %_ASM_AX

/* Enter guest mode */
--
2.22.0

2019-08-16 18:24:17

by Jim Mattson

Subject: Re: [PATCH] KVM: VMX: Fix and tweak the comments for VM-Enter

On Thu, Aug 15, 2019 at 1:11 PM Sean Christopherson
<[email protected]> wrote:
>
> Fix an incorrect/stale comment regarding the vmx_vcpu pointer, as guest
> registers are now loaded using a direct pointer to the start of the
> register array.
>
> Opportunistically add a comment to document why the vmx_vcpu pointer is
> needed, its consumption via 'call vmx_update_host_rsp' is rather subtle.
>
> Signed-off-by: Sean Christopherson <[email protected]>
Reviewed-by: Jim Mattson <[email protected]>

2019-08-19 15:50:33

by Paolo Bonzini

Subject: Re: [PATCH] KVM: VMX: Fix and tweak the comments for VM-Enter

On 15/08/19 22:09, Sean Christopherson wrote:
> Fix an incorrect/stale comment regarding the vmx_vcpu pointer, as guest
> registers are now loaded using a direct pointer to the start of the
> register array.
>
> Opportunistically add a comment to document why the vmx_vcpu pointer is
> needed, its consumption via 'call vmx_update_host_rsp' is rather subtle.
>
> Signed-off-by: Sean Christopherson <[email protected]>
> ---
> arch/x86/kvm/vmx/vmenter.S | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S
> index 4010d519eb8c..751a384c2eb0 100644
> --- a/arch/x86/kvm/vmx/vmenter.S
> +++ b/arch/x86/kvm/vmx/vmenter.S
> @@ -94,7 +94,7 @@ ENDPROC(vmx_vmexit)
>
> /**
> * __vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode
> - * @vmx: struct vcpu_vmx *
> + * @vmx: struct vcpu_vmx * (forwarded to vmx_update_host_rsp)
> * @regs: unsigned long * (to guest registers)
> * @launched: %true if the VMCS has been launched
> *
> @@ -151,7 +151,7 @@ ENTRY(__vmx_vcpu_run)
> mov VCPU_R14(%_ASM_AX), %r14
> mov VCPU_R15(%_ASM_AX), %r15
> #endif
> - /* Load guest RAX. This kills the vmx_vcpu pointer! */
> + /* Load guest RAX. This kills the @regs pointer! */
> mov VCPU_RAX(%_ASM_AX), %_ASM_AX
>
> /* Enter guest mode */
>

Queued, thanks.

Paolo