[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <400c0d11-fa14-cb1c-f6ed-02f850753e46@linux.intel.com>
Date: Wed, 12 Jul 2023 12:27:18 -0700
From: Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Kai Huang <kai.huang@...el.com>, peterz@...radead.org,
kirill.shutemov@...ux.intel.com, linux-kernel@...r.kernel.org
Cc: dave.hansen@...el.com, tglx@...utronix.de, bp@...en8.de,
mingo@...hat.com, hpa@...or.com, x86@...nel.org, seanjc@...gle.com,
pbonzini@...hat.com, kvm@...r.kernel.org, isaku.yamahata@...el.com
Subject: Re: [PATCH 02/10] x86/tdx: Use cmovc to save a label in
TDX_MODULE_CALL asm
On 7/12/23 1:55 AM, Kai Huang wrote:
> Change 'jnc .Lno_vmfailinvalid' to 'cmovc %rdi, %rax' to save the
> .Lno_vmfailinvalid label in the TDX_MODULE_CALL asm macro.
You are removing the label, right? What use "save"?
>
> Note %rdi, which is used as the first argument, has been saved to %rax
> as TDCALL leaf ID thus is free to hold the error code for cmovc.
>
> This is basically based on Peter's code.
>
> Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Suggested-by: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Kai Huang <kai.huang@...el.com>
> ---
> arch/x86/virt/vmx/tdx/tdxcall.S | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/virt/vmx/tdx/tdxcall.S b/arch/x86/virt/vmx/tdx/tdxcall.S
> index 49a54356ae99..3524915d8bd9 100644
> --- a/arch/x86/virt/vmx/tdx/tdxcall.S
> +++ b/arch/x86/virt/vmx/tdx/tdxcall.S
> @@ -57,10 +57,8 @@
> * This value will never be used as actual SEAMCALL error code as
> * it is from the Reserved status code class.
> */
> - jnc .Lno_vmfailinvalid
> - mov $TDX_SEAMCALL_VMFAILINVALID, %rax
> -.Lno_vmfailinvalid:
> -
> + mov $TDX_SEAMCALL_VMFAILINVALID, %rdi
> + cmovc %rdi, %rax
> .else
> tdcall
> .endif
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
Powered by blists - more mailing lists