From fd2d6e5623acae8b935c2ee5cb03d1a1b1631bb9 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 18 Jul 2025 18:03:48 +0200 Subject: [PATCH 081/115] i386/tdx: Don't treat SYSCALL as unavailable RH-Author: Paolo Bonzini RH-MergeRequest: 391: TDX support, including attestation and device assignment RH-Jira: RHEL-15710 RHEL-20798 RHEL-49728 RH-Acked-by: Yash Mankad RH-Acked-by: Peter Xu RH-Acked-by: David Hildenbrand RH-Commit: [81/115] f742fd685ae68e7828947fa1013a5bdb0b49750d (bonzini/rhel-qemu-kvm) On Intel CPU, the value of CPUID_EXT2_SYSCALL depends on the mode of the vcpu. It's 0 outside 64-bit mode and 1 in 64-bit mode. The initial state of TDX vcpu is 32-bit protected mode. At the time of calling KVM_TDX_GET_CPUID, vcpu hasn't started running so the value read is 0. In reality, 64-bit mode should always be supported. So mark CPUID_EXT2_SYSCALL always supported to avoid false warning. Signed-off-by: Xiaoyao Li Reviewed-by: Zhao Liu Link: https://lore.kernel.org/r/20250508150002.689633-53-xiaoyao.li@intel.com Signed-off-by: Paolo Bonzini (cherry picked from commit deb9db6fb789cfe80527b75983e86137589227a4) Signed-off-by: Paolo Bonzini --- target/i386/kvm/tdx.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c index 01fff9a27a..3e23010094 100644 --- a/target/i386/kvm/tdx.c +++ b/target/i386/kvm/tdx.c @@ -845,6 +845,19 @@ static int tdx_check_features(X86ConfidentialGuest *cg, CPUState *cs) continue; } + /* Fixup for special cases */ + switch (w) { + case FEAT_8000_0001_EDX: + /* + * Intel enumerates SYSCALL bit as 1 only when processor in 64-bit + * mode and before vcpu running it's not in 64-bit mode. + */ + actual |= CPUID_EXT2_SYSCALL; + break; + default: + break; + } + requested = env->features[w]; unavailable = requested & ~actual; mark_unavailable_features(cpu, w, unavailable, unav_prefix); -- 2.50.1