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UefiCpuPkg/CpuExceptionHandler: Add base support for the #VC exception

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BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198

Add base support to handle #VC exceptions. Update the common exception
handlers to invoke the VmgExitHandleVc () function of the VmgExitLib
library when a #VC is encountered. A non-zero return code will propagate
to the targeted exception handler.

Under SEV-ES, a DR7 read or write intercept generates a #VC exception.
To avoid exception recursion, a #VC exception will not try to read and
push the actual debug registers into the EFI_SYSTEM_CONTEXT_X64 struct
and instead push zeroes. The #VC exception handler does not make use of
the debug registers from the saved context and the exception processing
exit code does not attempt to restore the debug register values.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Tom Lendacky
2020-08-12 15:21:36 -05:00
committed by mergify[bot]
parent 3a4a6ead32
commit 5277540e37
10 changed files with 86 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/Xcode5ExceptionHandlerAsm.nasm
View File

@ -18,6 +18,8 @@
; CommonExceptionHandler()
;
%define VC_EXCEPTION 29
extern ASM_PFX(mErrorCodeFlag) ; Error code flags for exceptions
extern ASM_PFX(mDoFarReturnFlag) ; Do far return flag
extern ASM_PFX(CommonExceptionHandler)
@ -225,6 +227,9 @@ HasErrorCode:
push rax
;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
cmp qword [rbp + 8], VC_EXCEPTION
je VcDebugRegs ; For SEV-ES (#VC) Debug registers ignored
mov rax, dr7
push rax
mov rax, dr6
@ -237,7 +242,19 @@ HasErrorCode:
push rax
mov rax, dr0
push rax
jmp DrFinish
VcDebugRegs:
;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7 are skipped for #VC to avoid exception recursion
xor rax, rax
push rax
push rax
push rax
push rax
push rax
push rax
DrFinish:
;; FX_SAVE_STATE_X64 FxSaveState;
sub rsp, 512
mov rdi, rsp