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

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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@xxxxxxxxx/

Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
---
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{




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