On Tue, Apr 01, 2025 at 09:01:22AM -0400, Xiaoyao Li wrote:
> Validate TD attributes with tdx_caps that only supported bits are
> allowed by KVM.
>
> Besides, sanity check the attribute bits that have not been supported by
> QEMU yet. e.g., debug bit, it will be allowed in the future when debug
> TD support lands in QEMU.
>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Acked-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
> Changes in v8:
> - Split the mrconfigid/mrowner/mrownerconfig part into a seperate next
> patch;
>
> Changes in v7:
> - Define TDX_SUPPORTED_TD_ATTRS as QEMU supported mask, to validates
> user's request. (Rick)
>
> Changes in v3:
> - using error_setg() for error report; (Daniel)
> ---
> target/i386/kvm/tdx.c | 32 ++++++++++++++++++++++++++++++--
> 1 file changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
> index 1202b2111ba8..aa043acb1a88 100644
> --- a/target/i386/kvm/tdx.c
> +++ b/target/i386/kvm/tdx.c
> @@ -18,10 +18,15 @@
> #include "kvm_i386.h"
> #include "tdx.h"
>
> +#define TDX_TD_ATTRIBUTES_DEBUG BIT_ULL(0)
> #define TDX_TD_ATTRIBUTES_SEPT_VE_DISABLE BIT_ULL(28)
> #define TDX_TD_ATTRIBUTES_PKS BIT_ULL(30)
> #define TDX_TD_ATTRIBUTES_PERFMON BIT_ULL(63)
>
> +#define TDX_SUPPORTED_TD_ATTRS (TDX_TD_ATTRIBUTES_SEPT_VE_DISABLE |\
> + TDX_TD_ATTRIBUTES_PKS | \
> + TDX_TD_ATTRIBUTES_PERFMON)
> +
> static TdxGuest *tdx_guest;
>
> static struct kvm_tdx_capabilities *tdx_caps;
> @@ -153,13 +158,33 @@ static int tdx_kvm_type(X86ConfidentialGuest *cg)
> return KVM_X86_TDX_VM;
> }
>
> -static void setup_td_guest_attributes(X86CPU *x86cpu)
> +static int tdx_validate_attributes(TdxGuest *tdx, Error **errp)
> +{
> + if ((tdx->attributes & ~tdx_caps->supported_attrs)) {
> + error_setg(errp, "Invalid attributes 0x%lx for TDX VM "
> + "(KVM supported: 0x%llx)", tdx->attributes,
> + tdx_caps->supported_attrs);
> + return -1;
> + }
> +
> + if (tdx->attributes & ~TDX_SUPPORTED_TD_ATTRS) {
> + warn_report("Some QEMU unsupported TD attribute bits being requested:"
> + "requested: 0x%lx QEMU supported: 0x%llx",
> + tdx->attributes, TDX_SUPPORTED_TD_ATTRS);
IIUC, this is an explicit user mis-configuration, and so we
ought to use error_setg & return -1, not merely a warning.
> + }
> +
> + return 0;
> +}
> +
> +static int setup_td_guest_attributes(X86CPU *x86cpu, Error **errp)
> {
> CPUX86State *env = &x86cpu->env;
>
> tdx_guest->attributes |= (env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_PKS) ?
> TDX_TD_ATTRIBUTES_PKS : 0;
> tdx_guest->attributes |= x86cpu->enable_pmu ? TDX_TD_ATTRIBUTES_PERFMON : 0;
> +
> + return tdx_validate_attributes(tdx_guest, errp);
> }
>
> static int setup_td_xfam(X86CPU *x86cpu, Error **errp)
> @@ -225,7 +250,10 @@ int tdx_pre_create_vcpu(CPUState *cpu, Error **errp)
> init_vm = g_malloc0(sizeof(struct kvm_tdx_init_vm) +
> sizeof(struct kvm_cpuid_entry2) * KVM_MAX_CPUID_ENTRIES);
>
> - setup_td_guest_attributes(x86cpu);
> + r = setup_td_guest_attributes(x86cpu, errp);
> + if (r) {
> + return r;
> + }
>
> r = setup_td_xfam(x86cpu, errp);
> if (r) {
> --
> 2.34.1
>
With regards,
Daniel
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