OvmfPkg/ResetVector: add the macro to request guest termination

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

The upcoming SEV-SNP support will need to make a few additional guest
termination requests depending on the failure type. Let's move the logic
to request the guest termination into a macro to keep the code readable.

Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Acked-by: Ard Biesheuvel <ardb+tianocore@kernel.org>
Suggested-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

1 files changed, 45 insertions, 42 deletions

diff --git a/OvmfPkg/ResetVector/Ia32/AmdSev.asm b/OvmfPkg/ResetVector/Ia32/AmdSev.asm
index 93ba917f36..aa95d06ead 100644
--- a/OvmfPkg/ResetVector/Ia32/AmdSev.asm
+++ b/OvmfPkg/ResetVector/Ia32/AmdSev.asm
@@ -38,6 +38,13 @@ BITS    32
 %define SEV_GHCB_MSR                0xc0010130

 %define SEV_STATUS_MSR              0xc0010131

 

+; The #VC was not for CPUID

+%define TERM_VC_NOT_CPUID           1

+

+; The unexpected response code

+%define TERM_UNEXPECTED_RESP_CODE   2

+

+

 ; Macro is used to issue the MSR protocol based VMGEXIT. The caller is

 ; responsible to populate values in the EDX:EAX registers. After the vmmcall

 ; returns, it verifies that the response code matches with the expected

@@ -73,6 +80,43 @@ BITS    32
     jne     SevEsUnexpectedRespTerminate

 %endmacro

 

+; Macro to terminate the guest using the VMGEXIT.

+; arg 1: reason code

+%macro TerminateVmgExit 1

+    mov     eax, %1

+    ;

+    ; Use VMGEXIT to request termination. At this point the reason code is

+    ; located in EAX, so shift it left 16 bits to the proper location.

+    ;

+    ; EAX[11:0]  => 0x100 - request termination

+    ; EAX[15:12] => 0x1   - OVMF

+    ; EAX[23:16] => 0xXX  - REASON CODE

+    ;

+    shl     eax, 16

+    or      eax, 0x1100

+    xor     edx, edx

+    mov     ecx, SEV_GHCB_MSR

+    wrmsr

+    ;

+    ; Issue VMGEXIT - NASM doesn't support the vmmcall instruction in 32-bit

+    ; mode, so work around this by temporarily switching to 64-bit mode.

+    ;

+BITS    64

+    rep     vmmcall

+BITS    32

+

+    ;

+    ; We shouldn't come back from the VMGEXIT, but if we do, just loop.

+    ;

+%%TerminateHlt:

+    hlt

+    jmp     %%TerminateHlt

+%endmacro

+

+; Terminate the guest due to unexpected response code.

+SevEsUnexpectedRespTerminate:

+    TerminateVmgExit    TERM_UNEXPECTED_RESP_CODE

+

 ; Check if Secure Encrypted Virtualization (SEV) features are enabled.

 ;

 ; Register usage is tight in this routine, so multiple calls for the

@@ -227,48 +271,7 @@ SevEsDisabled:
 ;

 

 SevEsIdtNotCpuid:

-    ;

-    ; Use VMGEXIT to request termination.

-    ;   1 - #VC was not for CPUID

-    ;

-    mov     eax, 1

-    jmp     SevEsIdtTerminate

-

-SevEsUnexpectedRespTerminate:

-    ;

-    ; Use VMGEXIT to request termination.

-    ;   2 - Unexpected Response is received

-    ;

-    mov     eax, 2

-

-SevEsIdtTerminate:

-    ;

-    ; Use VMGEXIT to request termination. At this point the reason code is

-    ; located in EAX, so shift it left 16 bits to the proper location.

-    ;

-    ; EAX[11:0]  => 0x100 - request termination

-    ; EAX[15:12] => 0x1   - OVMF

-    ; EAX[23:16] => 0xXX  - REASON CODE

-    ;

-    shl     eax, 16

-    or      eax, 0x1100

-    xor     edx, edx

-    mov     ecx, SEV_GHCB_MSR

-    wrmsr

-    ;

-    ; Issue VMGEXIT - NASM doesn't support the vmmcall instruction in 32-bit

-    ; mode, so work around this by temporarily switching to 64-bit mode.

-    ;

-BITS    64

-    rep     vmmcall

-BITS    32

-

-    ;

-    ; We shouldn't come back from the VMGEXIT, but if we do, just loop.

-    ;

-SevEsIdtHlt:

-    hlt

-    jmp     SevEsIdtHlt

+    TerminateVmgExit TERM_VC_NOT_CPUID

     iret

 

     ;