Re: [RFC PATCH V3 12/16] x86/sev: Add a #HV exception handler

[Tianyu Lan]

On 3/9/2023 7:48 PM, Gupta, Pankaj wrote:
> On 1/22/2023 3:46 AM, Tianyu Lan wrote:
> > From: Tianyu Lan <tiala@xxxxxxxxxxxxx>
> > +    UNWIND_HINT_IRET_REGS
> > +    ASM_CLAC
> > +    pushq    $-1            /* ORIG_RAX: no syscall to restart */
> > +
> > +    testb    $3, CS-ORIG_RAX(%rsp)
> > +    jnz    .Lfrom_usermode_switch_stack_\@
> > +
> > +    call    paranoid_entry
> > +
> > +    UNWIND_HINT_REGS
> > +
> > +    /*
> > +     * Switch off the IST stack to make it free for nested exceptions.
> > +     */
> > +    movq    %rsp, %rdi        /* pt_regs pointer */
> > +    call    hv_switch_off_ist
> > +    movq    %rax, %rsp        /* Switch to new stack */
> > +
>
> We need "ENCODE_FRAME_POINTER" similar to "vc_switch_off_ist" here as we 
> are switching stack?

Agree. Will add it into the next version. Thanks.