On 3/28/2024 9:12 AM, Edgecombe, Rick P wrote:
On Thu, 2024-03-21 at 08:55 -0700, Isaku Yamahata wrote:
On Wed, Mar 20, 2024 at 02:12:49PM +0800,
Chao Gao <chao.gao@xxxxxxxxx> wrote:
+static void setup_tdparams_cpuids(struct kvm_cpuid2 *cpuid,
+ struct td_params *td_params)
+{
+ int i;
+
+ /*
+ * td_params.cpuid_values: The number and the order of cpuid_value must
+ * be same to the one of struct tdsysinfo.{num_cpuid_config, cpuid_configs}
+ * It's assumed that td_params was zeroed.
+ */
+ for (i = 0; i < tdx_info->num_cpuid_config; i++) {
+ const struct kvm_tdx_cpuid_config *c = &tdx_info->cpuid_configs[i];
+ /* KVM_TDX_CPUID_NO_SUBLEAF means index = 0. */
+ u32 index = c->sub_leaf == KVM_TDX_CPUID_NO_SUBLEAF ? 0 : c->sub_leaf;
+ const struct kvm_cpuid_entry2 *entry =
+ kvm_find_cpuid_entry2(cpuid->entries, cpuid->nent,
+ c->leaf, index);
+ struct tdx_cpuid_value *value = &td_params->cpuid_values[i];
+
+ if (!entry)
+ continue;
+
+ /*
+ * tdsysinfo.cpuid_configs[].{eax, ebx, ecx, edx}
+ * bit 1 means it can be configured to zero or one.
+ * bit 0 means it must be zero.
+ * Mask out non-configurable bits.
+ */
+ value->eax = entry->eax & c->eax;
+ value->ebx = entry->ebx & c->ebx;
+ value->ecx = entry->ecx & c->ecx;
+ value->edx = entry->edx & c->edx;
Any reason to mask off non-configurable bits rather than return an error? this
is misleading to userspace because guest sees the values emulated by TDX module
instead of the values passed from userspace (i.e., the request from userspace
isn't done but there is no indication of that to userspace).
Ok, I'll eliminate them. If user space passes wrong cpuids, TDX module will
return error. I'll leave the error check to the TDX module.
I was just looking at this. Agreed. It breaks the selftests though.
If all you prefer to go this direction, then please update the error
handling of this specific SEAMCALL.
