Re: [Xen-devel] [PATCH 4/9] x86/vvmx: Remove unnecessary VMX operand reads

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Euan Harris [mailto:euan.harris@xxxxxxxxxx]
> Sent: Friday, October 27, 2017 1:03 AM
> 
>  * vpid is never used in nvmx_handle_invept() so there is no point in
>    reading it.

I think you meant nvmx_handle_invvpid

> 
>  * vmptrst's operand is the memory address to which to write the VMCS
>    pointer.   gpa is the pointer to write.   Reading the address into
>    gpa is meaningless.
> 
> Signed-off-by: Euan Harris <euan.harris@xxxxxxxxxx>
> ---
>  xen/arch/x86/hvm/vmx/vvmx.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/vmx/vvmx.c
> b/xen/arch/x86/hvm/vmx/vvmx.c
> index df84592490..32c07eca3d 100644
> --- a/xen/arch/x86/hvm/vmx/vvmx.c
> +++ b/xen/arch/x86/hvm/vmx/vvmx.c
> @@ -1801,7 +1801,7 @@ int nvmx_handle_vmptrst(struct cpu_user_regs
> *regs)
>      unsigned long gpa = 0;
>      int rc;
> 
> -    rc = decode_vmx_inst(regs, &decode, &gpa, 0);
> +    rc = decode_vmx_inst(regs, &decode, NULL, 0);
>      if ( rc != X86EMUL_OKAY )
>          return rc;
> 
> @@ -1992,10 +1992,9 @@ int nvmx_handle_invept(struct cpu_user_regs
> *regs)
>  int nvmx_handle_invvpid(struct cpu_user_regs *regs)
>  {
>      struct vmx_inst_decoded decode;
> -    unsigned long vpid;
>      int ret;
> 
> -    if ( (ret = decode_vmx_inst(regs, &decode, &vpid, 0)) != X86EMUL_OKAY )
> +    if ( (ret = decode_vmx_inst(regs, &decode, NULL, 0)) != X86EMUL_OKAY )
>          return ret;
> 
>      switch ( reg_read(regs, decode.op[1].reg_idx) )
> --
> 2.13.6


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