On 5/13/2022 2:04 AM, Isaku Yamahata wrote:
> On Thu, May 12, 2022 at 11:17:41AM +0800,
> Xiaoyao Li <xiaoyao.li@intel.com> wrote:
>
>> Reuse "-cpu,tsc-frequency=" to get user wanted tsc frequency and pass it
>> to KVM_TDX_INIT_VM.
>>
>> Besides, sanity check the tsc frequency to be in the legal range and
>> legal granularity (required by TDX module).
>
> Just to make it sure.
> You didn't use VM-scoped KVM_SET_TSC_KHZ because KVM side patch is still in
> kvm/queue? Once the patch lands, we should use it.
I didn't use VM-scoped KVM_SET_TSC_KHZ is because
1) corresponding TDX KVM v6 series still provides tsc_khz in
struct kvm_tdx_init_vm
2) Use KVM_SET_TSC_KHZ to set VM-scoped TSC seems possible to be applied
to all VMs, not limited to TDs. It doesn't look like a small task.
I need more time to evaluate the efforts.
> Thanks,
>
>>
>> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
>> ---
>> target/i386/kvm/kvm.c | 8 ++++++++
>> target/i386/kvm/tdx.c | 18 ++++++++++++++++++
>> 2 files changed, 26 insertions(+)
>>
>> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
>> index f2d7c3cf59ac..c51125ab200f 100644
>> --- a/target/i386/kvm/kvm.c
>> +++ b/target/i386/kvm/kvm.c
>> @@ -818,6 +818,14 @@ static int kvm_arch_set_tsc_khz(CPUState *cs)
>> int r, cur_freq;
>> bool set_ioctl = false;
>>
>> + /*
>> + * TD guest's TSC is immutable, it cannot be set/changed via
>> + * KVM_SET_TSC_KHZ, but only be initialized via KVM_TDX_INIT_VM
>> + */
>> + if (is_tdx_vm()) {
>> + return 0;
>> + }
>> +
>> if (!env->tsc_khz) {
>> return 0;
>> }
>> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
>> index 9f2cdf640b5c..622efc409438 100644
>> --- a/target/i386/kvm/tdx.c
>> +++ b/target/i386/kvm/tdx.c
>> @@ -35,6 +35,9 @@
>> #define TDX_TD_ATTRIBUTES_PKS BIT_ULL(30)
>> #define TDX_TD_ATTRIBUTES_PERFMON BIT_ULL(63)
>>
>> +#define TDX_MIN_TSC_FREQUENCY_KHZ (100 * 1000)
>> +#define TDX_MAX_TSC_FREQUENCY_KHZ (10 * 1000 * 1000)
>> +
>> static TdxGuest *tdx_guest;
>>
>> /* It's valid after kvm_confidential_guest_init()->kvm_tdx_init() */
>> @@ -211,6 +214,20 @@ int tdx_pre_create_vcpu(CPUState *cpu)
>> goto out;
>> }
>>
>> + r = -EINVAL;
>> + if (env->tsc_khz && (env->tsc_khz < TDX_MIN_TSC_FREQUENCY_KHZ ||
>> + env->tsc_khz > TDX_MAX_TSC_FREQUENCY_KHZ)) {
>> + error_report("Invalid TSC %ld KHz, must specify cpu_frequency between [%d, %d] kHz",
>> + env->tsc_khz, TDX_MIN_TSC_FREQUENCY_KHZ,
>> + TDX_MAX_TSC_FREQUENCY_KHZ);
>> + goto out;
>> + }
>> +
>> + if (env->tsc_khz % (25 * 1000)) {
>> + error_report("Invalid TSC %ld KHz, it must be multiple of 25MHz", env->tsc_khz);
>> + goto out;
>> + }
>> +
>> r = setup_td_guest_attributes(x86cpu);
>> if (r) {
>> goto out;
>> @@ -221,6 +238,7 @@ int tdx_pre_create_vcpu(CPUState *cpu)
>>
>> init_vm.attributes = tdx_guest->attributes;
>> init_vm.max_vcpus = ms->smp.cpus;
>> + init_vm.tsc_khz = env->tsc_khz;
>>
>> r = tdx_vm_ioctl(KVM_TDX_INIT_VM, 0, &init_vm);
>> if (r < 0) {
>> --
>> 2.27.0
>>
>>
>