[v5] QEMU Guest memfd + QEMU TDX support

[PATCH v5 18/65] i386/tdx: Make Intel-PT unsupported for TD guest

Posted by Xiaoyao Li 1 year, 9 months ago

Due to the fact that Intel-PT virtualization support has been broken in
QEMU since Sapphire Rapids generation[1], below warning is triggered when
luanching TD guest:

  warning: host doesn't support requested feature: CPUID.07H:EBX.intel-pt [bit 25]

Before Intel-pt is fixed in QEMU, just make Intel-PT unsupported for TD
guest, to avoid the confusing warning.

[1] https://lore.kernel.org/qemu-devel/20230531084311.3807277-1-xiaoyao.li@intel.com/

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
Changes in v4:
 - newly added patch;
---
 target/i386/kvm/tdx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 85d96140b450..239170142e4f 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -292,6 +292,11 @@ void tdx_get_supported_cpuid(uint32_t function, uint32_t index, int reg,
     if (function == 1 && reg == R_ECX && !enable_cpu_pm) {
         *ret &= ~CPUID_EXT_MONITOR;
     }
+
+    /* QEMU Intel-pt support is broken, don't advertise Intel-PT */
+    if (function == 7 && reg == R_EBX) {
+        *ret &= ~CPUID_7_0_EBX_INTEL_PT;
+    }
 }
 
 enum tdx_ioctl_level{
-- 
2.34.1

Re: [PATCH v5 18/65] i386/tdx: Make Intel-PT unsupported for TD guest

Posted by Duan, Zhenzhong 1 year, 6 months ago

On 2/29/2024 2:36 PM, Xiaoyao Li wrote:
> Due to the fact that Intel-PT virtualization support has been broken in
> QEMU since Sapphire Rapids generation[1], below warning is triggered when
> luanching TD guest:
>
>    warning: host doesn't support requested feature: CPUID.07H:EBX.intel-pt [bit 25]
>
> Before Intel-pt is fixed in QEMU, just make Intel-PT unsupported for TD
> guest, to avoid the confusing warning.

I guess normal guest has same issue.

Thanks

Zhenzhong

>
> [1] https://lore.kernel.org/qemu-devel/20230531084311.3807277-1-xiaoyao.li@intel.com/
>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> ---
> Changes in v4:
>   - newly added patch;
> ---
>   target/i386/kvm/tdx.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
> index 85d96140b450..239170142e4f 100644
> --- a/target/i386/kvm/tdx.c
> +++ b/target/i386/kvm/tdx.c
> @@ -292,6 +292,11 @@ void tdx_get_supported_cpuid(uint32_t function, uint32_t index, int reg,
>       if (function == 1 && reg == R_ECX && !enable_cpu_pm) {
>           *ret &= ~CPUID_EXT_MONITOR;
>       }
> +
> +    /* QEMU Intel-pt support is broken, don't advertise Intel-PT */
> +    if (function == 7 && reg == R_EBX) {
> +        *ret &= ~CPUID_7_0_EBX_INTEL_PT;
> +    }
>   }
>   
>   enum tdx_ioctl_level{

Re: [PATCH v5 18/65] i386/tdx: Make Intel-PT unsupported for TD guest

Posted by Xiaoyao Li 1 year, 6 months ago

On 5/31/2024 5:27 PM, Duan, Zhenzhong wrote:
> 
> On 2/29/2024 2:36 PM, Xiaoyao Li wrote:
>> Due to the fact that Intel-PT virtualization support has been broken in
>> QEMU since Sapphire Rapids generation[1], below warning is triggered when
>> luanching TD guest:
>>
>>    warning: host doesn't support requested feature: 
>> CPUID.07H:EBX.intel-pt [bit 25]
>>
>> Before Intel-pt is fixed in QEMU, just make Intel-PT unsupported for TD
>> guest, to avoid the confusing warning.
> 
> I guess normal guest has same issue.

yeah, just the bug referenced by [1]

> Thanks
> 
> Zhenzhong
> 
>>
>> [1] 
>> https://lore.kernel.org/qemu-devel/20230531084311.3807277-1-xiaoyao.li@intel.com/
>>
>> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
>> ---
>> Changes in v4:
>>   - newly added patch;
>> ---
>>   target/i386/kvm/tdx.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
>> index 85d96140b450..239170142e4f 100644
>> --- a/target/i386/kvm/tdx.c
>> +++ b/target/i386/kvm/tdx.c
>> @@ -292,6 +292,11 @@ void tdx_get_supported_cpuid(uint32_t function, 
>> uint32_t index, int reg,
>>       if (function == 1 && reg == R_ECX && !enable_cpu_pm) {
>>           *ret &= ~CPUID_EXT_MONITOR;
>>       }
>> +
>> +    /* QEMU Intel-pt support is broken, don't advertise Intel-PT */
>> +    if (function == 7 && reg == R_EBX) {
>> +        *ret &= ~CPUID_7_0_EBX_INTEL_PT;
>> +    }
>>   }
>>   enum tdx_ioctl_level{