15 Aug
2025
15 Aug
'25
2:20 a.m.
+static struct kvm_cpuid_entry2 *tdx_find_cpuid_config(struct kvm_tdx_capabilities *cap,
uint32_t leaf, uint32_t sub_leaf)+{
- struct kvm_cpuid_entry2 *config;
- uint32_t i;
- for (i = 0; i < cap->cpuid.nent; i++) {
config = &cap->cpuid.entries[i];if (config->function == leaf && config->index == sub_leaf)return config;- }
- return NULL;
+}
+#define XFEATURE_MASK_CET (XFEATURE_MASK_CET_USER | XFEATURE_MASK_CET_KERNEL)
One guess on what my feedback would be.
Move this to tools/testing/selftests/kvm/include/x86/processor.h?
or this is dead code as CET virtualization has not been merged. But I think in general adding a test case for a feature before KVM's support is merged should be acceptable. e.g., KVM-unit-tests has CET tests for a long time.
That said, I agree with Rick that the entire tdx_apply_cpuid_restrictions() is unnecessary, as the supported CPUIDs reported by KVM should be sane.
+static void tdx_apply_cpuid_restrictions(struct kvm_cpuid2 *cpuid_data) +{
- for (int i = 0; i < cpuid_data->nent; i++) {
struct kvm_cpuid_entry2 *e = &cpuid_data->entries[i];if (e->function == 0xd && e->index == 0) {/** TDX module requires both XTILE_{CFG, DATA} to be set.* Both bits are required for AMX to be functional.*/if ((e->eax & XFEATURE_MASK_XTILE) !=XFEATURE_MASK_XTILE) {e->eax &= ~XFEATURE_MASK_XTILE;}}if (e->function == 0xd && e->index == 1) {/** TDX doesn't support LBR yet.* Disable bits from the XCR0 register.*/e->ecx &= ~XFEATURE_MASK_LBR;/** TDX modules requires both CET_{U, S} to be set even* if only one is supported.*/if (e->ecx & XFEATURE_MASK_CET)e->ecx |= XFEATURE_MASK_CET;}- }
+}