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

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

[Sean Christopherson]

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 <sean.j.christopherson@intel.com>
---
 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

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

[Jim Mattson]

On Thu, Aug 15, 2019 at 1:11 PM Sean Christopherson
<sean.j.christopherson@intel.com> 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 <sean.j.christopherson@intel.com>
Reviewed-by: Jim Mattson <jmattson@google.com>

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

[Paolo Bonzini]

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 <sean.j.christopherson@intel.com>
> ---
>  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