On 3/11/2024 3:29 PM, Markus Armbruster wrote:
Xiaoyao Li <xiaoyao.li@xxxxxxxxx> writes:
On 3/7/2024 9:51 PM, Markus Armbruster wrote:
Xiaoyao Li <xiaoyao.li@xxxxxxxxx> writes:
On 2/29/2024 4:51 PM, Markus Armbruster wrote:
Xiaoyao Li <xiaoyao.li@xxxxxxxxx> writes:
Integrate TDX's TDX_REPORT_FATAL_ERROR into QEMU GuestPanic facility
Originated-from: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
---
Changes in v5:
- mention additional error information in gpa when it presents;
- refine the documentation; (Markus)
Changes in v4:
- refine the documentation; (Markus)
Changes in v3:
- Add docmentation of new type and struct; (Daniel)
- refine the error message handling; (Daniel)
---
qapi/run-state.json | 31 +++++++++++++++++++++--
system/runstate.c | 58 +++++++++++++++++++++++++++++++++++++++++++
target/i386/kvm/tdx.c | 24 +++++++++++++++++-
3 files changed, 110 insertions(+), 3 deletions(-)
diff --git a/qapi/run-state.json b/qapi/run-state.json
index dd0770b379e5..b71dd1884eb6 100644
--- a/qapi/run-state.json
+++ b/qapi/run-state.json
[...]
@@ -564,6 +567,30 @@
'psw-addr': 'uint64',
'reason': 'S390CrashReason'}}
+##
+# @GuestPanicInformationTdx:
+#
+# TDX Guest panic information specific to TDX, as specified in the
+# "Guest-Hypervisor Communication Interface (GHCI) Specification",
+# section TDG.VP.VMCALL<ReportFatalError>.
+#
+# @error-code: TD-specific error code
+#
+# @message: Human-readable error message provided by the guest. Not
+# to be trusted.
+#
+# @gpa: guest-physical address of a page that contains more verbose
+# error information, as zero-terminated string. Present when the
+# "GPA valid" bit (bit 63) is set in @error-code.
Uh, peeking at GHCI Spec section 3.4 TDG.VP.VMCALL<ReportFatalError>, I
see operand R12 consists of
bits name description
31:0 TD-specific error code TD-specific error code
Panic – 0x0.
Values – 0x1 to 0xFFFFFFFF
reserved.
62:32 TD-specific extended TD-specific extended error code.
error code TD software defined.
63 GPA Valid Set if the TD specified additional
information in the GPA parameter
(R13).
Is @error-code all of R12, or just bits 31:0?
If it's all of R12, description of @error-code as "TD-specific error
code" is misleading.
We pass all of R12 to @error_code.
Here it wants to use "error_code" as generic as the whole R12. Do you have any better description of it ?
Sadly, the spec is of no help: it doesn't name the entire thing, only
the three sub-fields TD-specific error code, TD-specific extended error
code, GPA valid.
We could take the hint, and provide the sub-fields instead:
* @error-code contains the TD-specific error code (bits 31:0)
* @extended-error-code contains the TD-specific extended error code
(bits 62:32)
* we don't need @gpa-valid, because it's the same as "@gpa is present"
If we decide to keep the single member, we do need another name for it.
@error-codes (plural) doesn't exactly feel wonderful, but it gives at
least a subtle hint that it's not just *the* error code.
The reason we only defined one single member, is that the
extended-error-code is not used now, and I believe it won't be used in
the near future.
Aha! Then I recommend
* @error-code contains the TD-specific error code (bits 31:0)
* Omit bits 62:32 from the reply; if we later find an actual use for
them, we can add a suitable member
* Omit bit 63, because it's the same as "@gpa is present"
If no objection from others, I will use @error-codes (plural) in the
next version.
I recommend to keep the @error-code name, but narrow its value to the
actual error code, i.e. bits 31:0.
It works for me. I will got this direction in the next version.
If it's just bits 31:0, then 'Present when the "GPA valid" bit (bit 63)
is set in @error-code' is wrong. Could go with 'Only present when the
guest provides this information'.
[...]
