Convert TDG.VP.VMCALL<ReportFatalError> to KVM_EXIT_SYSTEM_EVENT with
a new type KVM_SYSTEM_EVENT_TDX_FATAL and forward it to userspace for
handling.

TD guest can use TDG.VP.VMCALL<ReportFatalError> to report the fatal
error it has experienced.  This hypercall is special because TD guest
is requesting a termination with the error information, KVM needs to
forward the hypercall to userspace anyway, KVM doesn't do sanity checks
and let userspace decide what to do.

Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
---
Hypercalls exit to userspace breakout:
- New added.
  Implement one of the hypercalls need to exit to userspace for handling after
  reverting "KVM: TDX: Add KVM Exit for TDX TDG.VP.VMCALL", which tries to resolve
  Sean's comment.
  https://lore.kernel.org/kvm/Zg18ul8Q4PGQMWam@google.com/
- Use TDVMCALL_STATUS prefix for TDX call status codes (Binbin)
---
 Documentation/virt/kvm/api.rst |  8 ++++++
 arch/x86/kvm/vmx/tdx.c         | 50 ++++++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h       |  1 +
 3 files changed, 59 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index edc070c6e19b..bb39da72c647 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6815,6 +6815,7 @@ should put the acknowledged interrupt vector into the 'epr' field.
   #define KVM_SYSTEM_EVENT_WAKEUP         4
   #define KVM_SYSTEM_EVENT_SUSPEND        5
   #define KVM_SYSTEM_EVENT_SEV_TERM       6
+  #define KVM_SYSTEM_EVENT_TDX_FATAL      7
 			__u32 type;
                         __u32 ndata;
                         __u64 data[16];
@@ -6841,6 +6842,13 @@ Valid values for 'type' are:
    reset/shutdown of the VM.
  - KVM_SYSTEM_EVENT_SEV_TERM -- an AMD SEV guest requested termination.
    The guest physical address of the guest's GHCB is stored in `data[0]`.
+ - KVM_SYSTEM_EVENT_TDX_FATAL -- an TDX guest requested termination.
+   The error codes of the guest's GHCI is stored in `data[0]`.
+   If the bit 63 of `data[0]` is set, it indicates there is TD specified
+   additional information provided in a page, which is shared memory. The
+   guest physical address of the information page is stored in `data[1]`.
+   An optional error message is provided by `data[2]` ~ `data[9]`, which is
+   byte sequence, LSB filled first. Typically, ASCII code(0x20-0x7e) is filled.
  - KVM_SYSTEM_EVENT_WAKEUP -- the exiting vCPU is in a suspended state and
    KVM has recognized a wakeup event. Userspace may honor this event by
    marking the exiting vCPU as runnable, or deny it and call KVM_RUN again.
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 553f4cbe0693..a79f9ca962d1 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1093,6 +1093,54 @@ static int tdx_map_gpa(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+static int tdx_report_fatal_error(struct kvm_vcpu *vcpu)
+{
+	u64 reg_mask = kvm_rcx_read(vcpu);
+	u64* opt_regs;
+
+	/*
+	 * Skip sanity checks and let userspace decide what to do if sanity
+	 * checks fail.
+	 */
+	vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
+	vcpu->run->system_event.type = KVM_SYSTEM_EVENT_TDX_FATAL;
+	vcpu->run->system_event.ndata = 10;
+	/* Error codes. */
+	vcpu->run->system_event.data[0] = tdvmcall_a0_read(vcpu);
+	/* GPA of additional information page. */
+	vcpu->run->system_event.data[1] = tdvmcall_a1_read(vcpu);
+	/* Information passed via registers (up to 64 bytes). */
+	opt_regs = &vcpu->run->system_event.data[2];
+
+#define COPY_REG(REG, MASK)						\
+	do {								\
+		if (reg_mask & MASK)					\
+			*opt_regs = kvm_ ## REG ## _read(vcpu);		\
+		else							\
+			*opt_regs = 0;					\
+		opt_regs++;						\
+	} while (0)
+
+	/* The order is defined in GHCI. */
+	COPY_REG(r14, BIT_ULL(14));
+	COPY_REG(r15, BIT_ULL(15));
+	COPY_REG(rbx, BIT_ULL(3));
+	COPY_REG(rdi, BIT_ULL(7));
+	COPY_REG(rsi, BIT_ULL(6));
+	COPY_REG(r8, BIT_ULL(8));
+	COPY_REG(r9, BIT_ULL(9));
+	COPY_REG(rdx, BIT_ULL(2));
+
+	/*
+	 * Set the status code according to GHCI spec, although the vCPU may
+	 * not return back to guest.
+	 */
+	tdvmcall_set_return_code(vcpu, TDVMCALL_STATUS_SUCCESS);
+
+	/* Forward request to userspace. */
+	return 0;
+}
+
 static int handle_tdvmcall(struct kvm_vcpu *vcpu)
 {
 	if (tdvmcall_exit_type(vcpu))
@@ -1101,6 +1149,8 @@ static int handle_tdvmcall(struct kvm_vcpu *vcpu)
 	switch (tdvmcall_leaf(vcpu)) {
 	case TDVMCALL_MAP_GPA:
 		return tdx_map_gpa(vcpu);
+	case TDVMCALL_REPORT_FATAL_ERROR:
+		return tdx_report_fatal_error(vcpu);
 	default:
 		break;
 	}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 637efc055145..c173c8dfcf83 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -375,6 +375,7 @@ struct kvm_run {
 #define KVM_SYSTEM_EVENT_WAKEUP         4
 #define KVM_SYSTEM_EVENT_SUSPEND        5
 #define KVM_SYSTEM_EVENT_SEV_TERM       6
+#define KVM_SYSTEM_EVENT_TDX_FATAL      7
 			__u32 type;
 			__u32 ndata;
 			union {
-- 
2.46.0

On 12/1/2024 11:53 AM, Binbin Wu wrote:
> Convert TDG.VP.VMCALL<ReportFatalError> to KVM_EXIT_SYSTEM_EVENT with
> a new type KVM_SYSTEM_EVENT_TDX_FATAL and forward it to userspace for
> handling.
> 
> TD guest can use TDG.VP.VMCALL<ReportFatalError> to report the fatal
> error it has experienced.  This hypercall is special because TD guest
> is requesting a termination with the error information, KVM needs to
> forward the hypercall to userspace anyway, KVM doesn't do sanity checks
> and let userspace decide what to do.
> 
> Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
> ---
> Hypercalls exit to userspace breakout:
> - New added.
>    Implement one of the hypercalls need to exit to userspace for handling after
>    reverting "KVM: TDX: Add KVM Exit for TDX TDG.VP.VMCALL", which tries to resolve
>    Sean's comment.
>    https://lore.kernel.org/kvm/Zg18ul8Q4PGQMWam@google.com/
> - Use TDVMCALL_STATUS prefix for TDX call status codes (Binbin)
> ---
>   Documentation/virt/kvm/api.rst |  8 ++++++
>   arch/x86/kvm/vmx/tdx.c         | 50 ++++++++++++++++++++++++++++++++++
>   include/uapi/linux/kvm.h       |  1 +
>   3 files changed, 59 insertions(+)
> 
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index edc070c6e19b..bb39da72c647 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -6815,6 +6815,7 @@ should put the acknowledged interrupt vector into the 'epr' field.
>     #define KVM_SYSTEM_EVENT_WAKEUP         4
>     #define KVM_SYSTEM_EVENT_SUSPEND        5
>     #define KVM_SYSTEM_EVENT_SEV_TERM       6
> +  #define KVM_SYSTEM_EVENT_TDX_FATAL      7
>   			__u32 type;
>                           __u32 ndata;
>                           __u64 data[16];
> @@ -6841,6 +6842,13 @@ Valid values for 'type' are:
>      reset/shutdown of the VM.
>    - KVM_SYSTEM_EVENT_SEV_TERM -- an AMD SEV guest requested termination.
>      The guest physical address of the guest's GHCB is stored in `data[0]`.
> + - KVM_SYSTEM_EVENT_TDX_FATAL -- an TDX guest requested termination.
> +   The error codes of the guest's GHCI is stored in `data[0]`.
> +   If the bit 63 of `data[0]` is set, it indicates there is TD specified
> +   additional information provided in a page, which is shared memory. The
> +   guest physical address of the information page is stored in `data[1]`.
> +   An optional error message is provided by `data[2]` ~ `data[9]`, which is
> +   byte sequence, LSB filled first. Typically, ASCII code(0x20-0x7e) is filled.
>    - KVM_SYSTEM_EVENT_WAKEUP -- the exiting vCPU is in a suspended state and
>      KVM has recognized a wakeup event. Userspace may honor this event by
>      marking the exiting vCPU as runnable, or deny it and call KVM_RUN again.
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 553f4cbe0693..a79f9ca962d1 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -1093,6 +1093,54 @@ static int tdx_map_gpa(struct kvm_vcpu *vcpu)
>   	return 1;
>   }
>   
> +static int tdx_report_fatal_error(struct kvm_vcpu *vcpu)
> +{
> +	u64 reg_mask = kvm_rcx_read(vcpu);
> +	u64* opt_regs;
> +
> +	/*
> +	 * Skip sanity checks and let userspace decide what to do if sanity
> +	 * checks fail.
> +	 */
> +	vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
> +	vcpu->run->system_event.type = KVM_SYSTEM_EVENT_TDX_FATAL;
> +	vcpu->run->system_event.ndata = 10;
> +	/* Error codes. */
> +	vcpu->run->system_event.data[0] = tdvmcall_a0_read(vcpu);
> +	/* GPA of additional information page. */
> +	vcpu->run->system_event.data[1] = tdvmcall_a1_read(vcpu);
> +	/* Information passed via registers (up to 64 bytes). */
> +	opt_regs = &vcpu->run->system_event.data[2];
> +
> +#define COPY_REG(REG, MASK)						\
> +	do {								\
> +		if (reg_mask & MASK)					\
> +			*opt_regs = kvm_ ## REG ## _read(vcpu);		\
> +		else							\
> +			*opt_regs = 0;					\
> +		opt_regs++;						\

I'm not sure if we need to skip the "opt_regs++" the corresponding 
register is not set valid in reg_mask. And maintain ndata to actual 
valid number instead of hardcoding it to 10.

> +	} while (0)
> +
> +	/* The order is defined in GHCI. */
> +	COPY_REG(r14, BIT_ULL(14));
> +	COPY_REG(r15, BIT_ULL(15));
> +	COPY_REG(rbx, BIT_ULL(3));
> +	COPY_REG(rdi, BIT_ULL(7));
> +	COPY_REG(rsi, BIT_ULL(6));
> +	COPY_REG(r8, BIT_ULL(8));
> +	COPY_REG(r9, BIT_ULL(9));
> +	COPY_REG(rdx, BIT_ULL(2));
> +
> +	/*
> +	 * Set the status code according to GHCI spec, although the vCPU may
> +	 * not return back to guest.
> +	 */
> +	tdvmcall_set_return_code(vcpu, TDVMCALL_STATUS_SUCCESS);
> +
> +	/* Forward request to userspace. */
> +	return 0;
> +}
> +
>   static int handle_tdvmcall(struct kvm_vcpu *vcpu)
>   {
>   	if (tdvmcall_exit_type(vcpu))
> @@ -1101,6 +1149,8 @@ static int handle_tdvmcall(struct kvm_vcpu *vcpu)
>   	switch (tdvmcall_leaf(vcpu)) {
>   	case TDVMCALL_MAP_GPA:
>   		return tdx_map_gpa(vcpu);
> +	case TDVMCALL_REPORT_FATAL_ERROR:
> +		return tdx_report_fatal_error(vcpu);
>   	default:
>   		break;
>   	}
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 637efc055145..c173c8dfcf83 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -375,6 +375,7 @@ struct kvm_run {
>   #define KVM_SYSTEM_EVENT_WAKEUP         4
>   #define KVM_SYSTEM_EVENT_SUSPEND        5
>   #define KVM_SYSTEM_EVENT_SEV_TERM       6
> +#define KVM_SYSTEM_EVENT_TDX_FATAL      7
>   			__u32 type;
>   			__u32 ndata;
>   			union {

On 12/13/2024 5:40 PM, Xiaoyao Li wrote:
> On 12/1/2024 11:53 AM, Binbin Wu wrote:
>> Convert TDG.VP.VMCALL<ReportFatalError> to KVM_EXIT_SYSTEM_EVENT with
>> a new type KVM_SYSTEM_EVENT_TDX_FATAL and forward it to userspace for
>> handling.
>>
>> TD guest can use TDG.VP.VMCALL<ReportFatalError> to report the fatal
>> error it has experienced.  This hypercall is special because TD guest
>> is requesting a termination with the error information, KVM needs to
>> forward the hypercall to userspace anyway, KVM doesn't do sanity checks
>> and let userspace decide what to do.
>>
>> Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
>> ---
>> Hypercalls exit to userspace breakout:
>> - New added.
>>    Implement one of the hypercalls need to exit to userspace for handling after
>>    reverting "KVM: TDX: Add KVM Exit for TDX TDG.VP.VMCALL", which tries to resolve
>>    Sean's comment.
>>    https://lore.kernel.org/kvm/Zg18ul8Q4PGQMWam@google.com/
>> - Use TDVMCALL_STATUS prefix for TDX call status codes (Binbin)
>> ---
>>   Documentation/virt/kvm/api.rst |  8 ++++++
>>   arch/x86/kvm/vmx/tdx.c         | 50 ++++++++++++++++++++++++++++++++++
>>   include/uapi/linux/kvm.h       |  1 +
>>   3 files changed, 59 insertions(+)
>>
>> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
>> index edc070c6e19b..bb39da72c647 100644
>> --- a/Documentation/virt/kvm/api.rst
>> +++ b/Documentation/virt/kvm/api.rst
>> @@ -6815,6 +6815,7 @@ should put the acknowledged interrupt vector into the 'epr' field.
>>     #define KVM_SYSTEM_EVENT_WAKEUP         4
>>     #define KVM_SYSTEM_EVENT_SUSPEND        5
>>     #define KVM_SYSTEM_EVENT_SEV_TERM       6
>> +  #define KVM_SYSTEM_EVENT_TDX_FATAL      7
>>               __u32 type;
>>                           __u32 ndata;
>>                           __u64 data[16];
>> @@ -6841,6 +6842,13 @@ Valid values for 'type' are:
>>      reset/shutdown of the VM.
>>    - KVM_SYSTEM_EVENT_SEV_TERM -- an AMD SEV guest requested termination.
>>      The guest physical address of the guest's GHCB is stored in `data[0]`.
>> + - KVM_SYSTEM_EVENT_TDX_FATAL -- an TDX guest requested termination.
>> +   The error codes of the guest's GHCI is stored in `data[0]`.
>> +   If the bit 63 of `data[0]` is set, it indicates there is TD specified
>> +   additional information provided in a page, which is shared memory. The
>> +   guest physical address of the information page is stored in `data[1]`.
>> +   An optional error message is provided by `data[2]` ~ `data[9]`, which is
>> +   byte sequence, LSB filled first. Typically, ASCII code(0x20-0x7e) is filled.
>>    - KVM_SYSTEM_EVENT_WAKEUP -- the exiting vCPU is in a suspended state and
>>      KVM has recognized a wakeup event. Userspace may honor this event by
>>      marking the exiting vCPU as runnable, or deny it and call KVM_RUN again.
>> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
>> index 553f4cbe0693..a79f9ca962d1 100644
>> --- a/arch/x86/kvm/vmx/tdx.c
>> +++ b/arch/x86/kvm/vmx/tdx.c
>> @@ -1093,6 +1093,54 @@ static int tdx_map_gpa(struct kvm_vcpu *vcpu)
>>       return 1;
>>   }
>>   +static int tdx_report_fatal_error(struct kvm_vcpu *vcpu)
>> +{
>> +    u64 reg_mask = kvm_rcx_read(vcpu);
>> +    u64* opt_regs;
>> +
>> +    /*
>> +     * Skip sanity checks and let userspace decide what to do if sanity
>> +     * checks fail.
>> +     */
>> +    vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
>> +    vcpu->run->system_event.type = KVM_SYSTEM_EVENT_TDX_FATAL;
>> +    vcpu->run->system_event.ndata = 10;
>> +    /* Error codes. */
>> +    vcpu->run->system_event.data[0] = tdvmcall_a0_read(vcpu);
>> +    /* GPA of additional information page. */
>> +    vcpu->run->system_event.data[1] = tdvmcall_a1_read(vcpu);
>> +    /* Information passed via registers (up to 64 bytes). */
>> +    opt_regs = &vcpu->run->system_event.data[2];
>> +
>> +#define COPY_REG(REG, MASK)                        \
>> +    do {                                \
>> +        if (reg_mask & MASK)                    \
>> +            *opt_regs = kvm_ ## REG ## _read(vcpu);        \
>> +        else                            \
>> +            *opt_regs = 0;                    \
>> +        opt_regs++;                        \
>
> I'm not sure if we need to skip the "opt_regs++" the corresponding register is not set valid in reg_mask. And maintain ndata to actual valid number instead of hardcoding it to 10.
Yes, it's better.

>
>> +    } while (0)
>> +
>> +    /* The order is defined in GHCI. */
>> +    COPY_REG(r14, BIT_ULL(14));
>> +    COPY_REG(r15, BIT_ULL(15));
>> +    COPY_REG(rbx, BIT_ULL(3));
>> +    COPY_REG(rdi, BIT_ULL(7));
>> +    COPY_REG(rsi, BIT_ULL(6));
>> +    COPY_REG(r8, BIT_ULL(8));
>> +    COPY_REG(r9, BIT_ULL(9));
>> +    COPY_REG(rdx, BIT_ULL(2));
>> +
>> +    /*
>> +     * Set the status code according to GHCI spec, although the vCPU may
>> +     * not return back to guest.
>> +     */
>> +    tdvmcall_set_return_code(vcpu, TDVMCALL_STATUS_SUCCESS);
>> +
>> +    /* Forward request to userspace. */
>> +    return 0;
>> +}
>> +
>>   static int handle_tdvmcall(struct kvm_vcpu *vcpu)
>>   {
>>       if (tdvmcall_exit_type(vcpu))
>> @@ -1101,6 +1149,8 @@ static int handle_tdvmcall(struct kvm_vcpu *vcpu)
>>       switch (tdvmcall_leaf(vcpu)) {
>>       case TDVMCALL_MAP_GPA:
>>           return tdx_map_gpa(vcpu);
>> +    case TDVMCALL_REPORT_FATAL_ERROR:
>> +        return tdx_report_fatal_error(vcpu);
>>       default:
>>           break;
>>       }
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index 637efc055145..c173c8dfcf83 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -375,6 +375,7 @@ struct kvm_run {
>>   #define KVM_SYSTEM_EVENT_WAKEUP         4
>>   #define KVM_SYSTEM_EVENT_SUSPEND        5
>>   #define KVM_SYSTEM_EVENT_SEV_TERM       6
>> +#define KVM_SYSTEM_EVENT_TDX_FATAL      7
>>               __u32 type;
>>               __u32 ndata;
>>               union {
>
>

>diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
>index edc070c6e19b..bb39da72c647 100644
>--- a/Documentation/virt/kvm/api.rst
>+++ b/Documentation/virt/kvm/api.rst
>@@ -6815,6 +6815,7 @@ should put the acknowledged interrupt vector into the 'epr' field.
>   #define KVM_SYSTEM_EVENT_WAKEUP         4
>   #define KVM_SYSTEM_EVENT_SUSPEND        5
>   #define KVM_SYSTEM_EVENT_SEV_TERM       6
>+  #define KVM_SYSTEM_EVENT_TDX_FATAL      7
> 			__u32 type;
>                         __u32 ndata;
>                         __u64 data[16];
>@@ -6841,6 +6842,13 @@ Valid values for 'type' are:
>    reset/shutdown of the VM.
>  - KVM_SYSTEM_EVENT_SEV_TERM -- an AMD SEV guest requested termination.
>    The guest physical address of the guest's GHCB is stored in `data[0]`.
>+ - KVM_SYSTEM_EVENT_TDX_FATAL -- an TDX guest requested termination.

Not sure termination is an accurate interpretation of fatal errors. Maybe
just say: a fatal error reported by a TDX guest.

>+   The error codes of the guest's GHCI is stored in `data[0]`.

what do you mean by "guest's GHCI"?

>+   If the bit 63 of `data[0]` is set, it indicates there is TD specified
>+   additional information provided in a page, which is shared memory. The
>+   guest physical address of the information page is stored in `data[1]`.
>+   An optional error message is provided by `data[2]` ~ `data[9]`, which is
>+   byte sequence, LSB filled first. Typically, ASCII code(0x20-0x7e) is filled.
>  - KVM_SYSTEM_EVENT_WAKEUP -- the exiting vCPU is in a suspended state and
>    KVM has recognized a wakeup event. Userspace may honor this event by
>    marking the exiting vCPU as runnable, or deny it and call KVM_RUN again.

On 12/10/2024 5:05 PM, Chao Gao wrote:
>> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
>> index edc070c6e19b..bb39da72c647 100644
>> --- a/Documentation/virt/kvm/api.rst
>> +++ b/Documentation/virt/kvm/api.rst
>> @@ -6815,6 +6815,7 @@ should put the acknowledged interrupt vector into the 'epr' field.
>>    #define KVM_SYSTEM_EVENT_WAKEUP         4
>>    #define KVM_SYSTEM_EVENT_SUSPEND        5
>>    #define KVM_SYSTEM_EVENT_SEV_TERM       6
>> +  #define KVM_SYSTEM_EVENT_TDX_FATAL      7
>> 			__u32 type;
>>                          __u32 ndata;
>>                          __u64 data[16];
>> @@ -6841,6 +6842,13 @@ Valid values for 'type' are:
>>     reset/shutdown of the VM.
>>   - KVM_SYSTEM_EVENT_SEV_TERM -- an AMD SEV guest requested termination.
>>     The guest physical address of the guest's GHCB is stored in `data[0]`.
>> + - KVM_SYSTEM_EVENT_TDX_FATAL -- an TDX guest requested termination.
> Not sure termination is an accurate interpretation of fatal errors. Maybe
> just say: a fatal error reported by a TDX guest.
OK, will update it as:
"a TDX guest reported a fatal error state."

>
>> +   The error codes of the guest's GHCI is stored in `data[0]`.
> what do you mean by "guest's GHCI"?
I don't know what I was thinking about.

Will update it as:
    The error code reported by the TDX guest is stored in `data[0]`, the error
    code format is defined in TDX GHCI specification.

>
>> +   If the bit 63 of `data[0]` is set, it indicates there is TD specified
>> +   additional information provided in a page, which is shared memory. The
>> +   guest physical address of the information page is stored in `data[1]`.
>> +   An optional error message is provided by `data[2]` ~ `data[9]`, which is
>> +   byte sequence, LSB filled first. Typically, ASCII code(0x20-0x7e) is filled.
>>   - KVM_SYSTEM_EVENT_WAKEUP -- the exiting vCPU is in a suspended state and
>>     KVM has recognized a wakeup event. Userspace may honor this event by
>>     marking the exiting vCPU as runnable, or deny it and call KVM_RUN again.

> +static int tdx_report_fatal_error(struct kvm_vcpu *vcpu)
> +{
> +	u64 reg_mask = kvm_rcx_read(vcpu);
> +	u64* opt_regs;
> +
> +	/*
> +	 * Skip sanity checks and let userspace decide what to do if sanity
> +	 * checks fail.
> +	 */
> +	vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
> +	vcpu->run->system_event.type = KVM_SYSTEM_EVENT_TDX_FATAL;
> +	vcpu->run->system_event.ndata = 10;
> +	/* Error codes. */
> +	vcpu->run->system_event.data[0] = tdvmcall_a0_read(vcpu);
> +	/* GPA of additional information page. */
> +	vcpu->run->system_event.data[1] = tdvmcall_a1_read(vcpu);
> +	/* Information passed via registers (up to 64 bytes). */
> +	opt_regs = &vcpu->run->system_event.data[2];
> +
> +#define COPY_REG(REG, MASK)						\
> +	do {								\
> +		if (reg_mask & MASK)					\
> +			*opt_regs = kvm_ ## REG ## _read(vcpu);		\
> +		else							\
> +			*opt_regs = 0;					\
> +		opt_regs++;						\
> +	} while (0)
> +
> +	/* The order is defined in GHCI. */
> +	COPY_REG(r14, BIT_ULL(14));
> +	COPY_REG(r15, BIT_ULL(15));
> +	COPY_REG(rbx, BIT_ULL(3));
> +	COPY_REG(rdi, BIT_ULL(7));
> +	COPY_REG(rsi, BIT_ULL(6));
> +	COPY_REG(r8, BIT_ULL(8));
> +	COPY_REG(r9, BIT_ULL(9));
> +	COPY_REG(rdx, BIT_ULL(2));

Nit:

#undef COPY_REG

Thanks,
Yilun

> +
> +	/*
> +	 * Set the status code according to GHCI spec, although the vCPU may
> +	 * not return back to guest.
> +	 */
> +	tdvmcall_set_return_code(vcpu, TDVMCALL_STATUS_SUCCESS);
> +
> +	/* Forward request to userspace. */
> +	return 0;
> +}

On 12/6/2024 5:31 PM, Xu Yilun wrote:
>> +static int tdx_report_fatal_error(struct kvm_vcpu *vcpu)
>> +{
>> +	u64 reg_mask = kvm_rcx_read(vcpu);
>> +	u64* opt_regs;
>> +
>> +	/*
>> +	 * Skip sanity checks and let userspace decide what to do if sanity
>> +	 * checks fail.
>> +	 */
>> +	vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
>> +	vcpu->run->system_event.type = KVM_SYSTEM_EVENT_TDX_FATAL;
>> +	vcpu->run->system_event.ndata = 10;
>> +	/* Error codes. */
>> +	vcpu->run->system_event.data[0] = tdvmcall_a0_read(vcpu);
>> +	/* GPA of additional information page. */
>> +	vcpu->run->system_event.data[1] = tdvmcall_a1_read(vcpu);
>> +	/* Information passed via registers (up to 64 bytes). */
>> +	opt_regs = &vcpu->run->system_event.data[2];
>> +
>> +#define COPY_REG(REG, MASK)						\
>> +	do {								\
>> +		if (reg_mask & MASK)					\
>> +			*opt_regs = kvm_ ## REG ## _read(vcpu);		\
>> +		else							\
>> +			*opt_regs = 0;					\
>> +		opt_regs++;						\
>> +	} while (0)
>> +
>> +	/* The order is defined in GHCI. */
>> +	COPY_REG(r14, BIT_ULL(14));
>> +	COPY_REG(r15, BIT_ULL(15));
>> +	COPY_REG(rbx, BIT_ULL(3));
>> +	COPY_REG(rdi, BIT_ULL(7));
>> +	COPY_REG(rsi, BIT_ULL(6));
>> +	COPY_REG(r8, BIT_ULL(8));
>> +	COPY_REG(r9, BIT_ULL(9));
>> +	COPY_REG(rdx, BIT_ULL(2));
> Nit:
>
> #undef COPY_REG
Thanks for catching it!

>
> Thanks,
> Yilun
>
>> +
>> +	/*
>> +	 * Set the status code according to GHCI spec, although the vCPU may
>> +	 * not return back to guest.
>> +	 */
>> +	tdvmcall_set_return_code(vcpu, TDVMCALL_STATUS_SUCCESS);
>> +
>> +	/* Forward request to userspace. */
>> +	return 0;
>> +}