On Wed, Jun 12, 2019 at 04:41:02PM +0800, Like Xu wrote:
> In guest CPUID generation process, the cpuid_min_level would be adjusted to
> the maximum passed value for basic CPUID configuration and it should not be
> restricted by the limited value returned from cpu_x86_cpuid(). After the basic
> cpu_x86_cpuid() loop is finished, the cpuid_0_entry.eax needs to be configured
> again by the last adjusted cpuid_min_level value.
>
> If a user wants to expose CPUID.1F by passing dies > 1 for any reason without
> host support, a per-cpu smp topology warning will appear but it's not blocked.
>
> Signed-off-by: Like Xu <like...@linux.intel.com>
This code doesn't look at host CPUID at all, as far as I can see.
Isn't it simpler to just make cpuid_x86_cpuid() return the
correct data?
> ---
> target/i386/kvm.c | 24 ++++++++++++++++++++++--
> 1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index 9b4da9b265..8bf1604d2b 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -931,12 +931,12 @@ int kvm_arch_init_vcpu(CPUState *cs)
> struct kvm_cpuid_entry2 *c;
> uint32_t signature[3];
> int kvm_base = KVM_CPUID_SIGNATURE;
> - int r;
> + int r, cpuid_0_entry, cpuid_min_level;
> Error *local_err = NULL;
>
> memset(&cpuid_data, 0, sizeof(cpuid_data));
>
> - cpuid_i = 0;
> + cpuid_i = cpuid_0_entry = cpuid_min_level = 0;
>
> r = kvm_arch_set_tsc_khz(cs);
> if (r < 0) {
> @@ -1050,6 +1050,12 @@ int kvm_arch_init_vcpu(CPUState *cs)
>
> cpu_x86_cpuid(env, 0, 0, &limit, &unused, &unused, &unused);
>
> + /* Allow 0x1f setting regardless of kvm support if nr_dies > 1 */
> + if (limit < 0x1f && env->nr_dies > 1 && cpu->enable_cpuid_0x1f) {
> + limit = env->cpuid_level = env->cpuid_min_level = 0x1f;
> + warn_report("CPU topology: the CPUID.1F isn't supported on the
> host.");
> + }
> +
> for (i = 0; i <= limit; i++) {
> if (cpuid_i == KVM_MAX_CPUID_ENTRIES) {
> fprintf(stderr, "unsupported level value: 0x%x\n", limit);
> @@ -1151,8 +1157,22 @@ int kvm_arch_init_vcpu(CPUState *cs)
> cpu_x86_cpuid(env, i, 0, &c->eax, &c->ebx, &c->ecx, &c->edx);
> break;
> }
> +
> + /* Remember the index of cpuid.0 leaf for reconfiguration. */
> + cpuid_0_entry = (i == 0) ? (cpuid_i - 1) : cpuid_0_entry;
> +
> + /* Adjust cpuid_min_level to the maximum index of valid basic
> cpuids. */
> + cpuid_min_level =
> + ((c->eax | c->ebx | c->ecx | c->edx | c->flags | c->index) &&
> + (i > cpuid_min_level)) ? i : cpuid_min_level;
> }
>
> + env->cpuid_level = env->cpuid_min_level = cpuid_min_level;
> +
> + /* Reconfigure cpuid_0_eax value to follow CPUID.0 instruction spec.*/
> + c = &cpuid_data.entries[cpuid_0_entry];
> + cpu_x86_cpuid(env, 0, 0, &c->eax, &c->ebx, &c->ecx, &c->edx);
> +
> if (limit >= 0x0a) {
> uint32_t eax, edx;
>
> --
> 2.21.0
>
--
Eduardo
