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From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
	"Wei Liu" <wl@xen.org>, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH 4/4] x86/svm: Use named (bit)fields for task switch exit info
Date: Wed, 4 Dec 2019 11:24:40 +0100
Message-ID: <2d347b3a-7b2e-d28a-59d0-2206bc215206@suse.com> (raw)
In-Reply-To: <20191204094335.24603-5-andrew.cooper3@citrix.com>

On 04.12.2019 10:43, Andrew Cooper wrote:
> Introduce vmcb.e1.* and vmcb.e2.* to provide names to fields in exitinfo{1,2}
> respectively.  Implement the task switch names for now, and clean up the
> TASK_SWITCH handler.

"e1" and "e2" look overly short - and hence possibly ambiguous -
to me. Make them perhaps "ei1" and "ei2"? Furthermore, seeing ...

> @@ -2795,19 +2792,12 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
>          if ( insn_len < 0 && (insn_len = svm_get_task_switch_insn_len()) == 0 )
>              goto crash_or_fault;
>  
> -        if ( (vmcb->exitinfo2 >> 36) & 1 )
> -            reason = TSW_iret;
> -        else if ( (vmcb->exitinfo2 >> 38) & 1 )
> -            reason = TSW_jmp;
> -        else
> -            reason = TSW_call_or_int;
> -        if ( (vmcb->exitinfo2 >> 44) & 1 )
> -            errcode = (uint32_t)vmcb->exitinfo2;
> -
> -        hvm_task_switch(vmcb->exitinfo1, reason, errcode, insn_len,
> -                        (vmcb->exitinfo2 & (1ul << 48)) ? X86_EFLAGS_RF : 0);
> +        hvm_task_switch(vmcb->e1.task_switch.sel,
> +                        vmcb->e2.task_switch.iret ? TSW_iret :
> +                        vmcb->e2.task_switch.jmp  ? TSW_jmp : TSW_call_or_int,
> +                        vmcb->e2.task_switch.ev ? vmcb->e2.task_switch.ec : -1,
> +                        insn_len, vmcb->e2.task_switch.rf ? X86_EFLAGS_RF : 0);

... this, wouldn't it make sense to simply have "ei" covering both
parts, no longer making it a requirement to use (and hence look up)
the numeric suffixes at use sites?

> --- a/xen/include/asm-x86/hvm/svm/vmcb.h
> +++ b/xen/include/asm-x86/hvm/svm/vmcb.h
> @@ -418,8 +418,30 @@ struct vmcb_struct {
>      vintr_t _vintr;             /* offset 0x60 - cleanbit 3 */
>      u64 interrupt_shadow;       /* offset 0x68 */
>      u64 exitcode;               /* offset 0x70 */
> -    u64 exitinfo1;              /* offset 0x78 */
> -    u64 exitinfo2;              /* offset 0x80 */
> +    union {
> +        u64 exitinfo1;          /* offset 0x78 */

uint64_t (also below)?

Jan

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Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-04  9:43 [Xen-devel] [PATCH 0/4] x86/svm: (Post TASK_SWITCH) cleanup Andrew Cooper
2019-12-04  9:43 ` [Xen-devel] [PATCH 1/4] x86/svm: Clean up construct_vmcb() Andrew Cooper
2019-12-04 10:06   ` Jan Beulich
2019-12-04 19:21     ` Andrew Cooper
2019-12-04  9:43 ` [Xen-devel] [PATCH 2/4] x86/svm: Don't shadow variables in svm_vmexit_handler() Andrew Cooper
2019-12-04 10:10   ` Jan Beulich
2019-12-04  9:43 ` [Xen-devel] [PATCH 3/4] x86/svm: Clean up intinfo_t variables Andrew Cooper
2019-12-04 10:19   ` Jan Beulich
2019-12-04 19:22     ` Andrew Cooper
2019-12-04 19:38   ` Andrew Cooper
2019-12-05  9:11     ` Jan Beulich
2019-12-05 12:33   ` Andrew Cooper
2019-12-04  9:43 ` [Xen-devel] [PATCH 4/4] x86/svm: Use named (bit)fields for task switch exit info Andrew Cooper
2019-12-04 10:24   ` Jan Beulich [this message]
2019-12-04 20:04     ` Andrew Cooper
2019-12-05  9:05       ` Jan Beulich
2019-12-05 10:51 ` [Xen-devel] [PATCH 5/4] x86/svm: Minor cleanup to start_svm() Andrew Cooper
2019-12-05 10:53   ` Jan Beulich

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