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

From: Tianyu Lan
Date: Fri Mar 10 2023 - 10:56:31 EST



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.