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Merge branch 'kvm-pre-tdx' into HEAD

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- Add common secure TSC infrastructure for use within SNP and in the
  future TDX

- Block KVM_CAP_SYNC_REGS if guest state is protected.  It does not make
  sense to use the capability if the relevant registers are not
  available for reading or writing.
This commit is contained in:
Paolo Bonzini
2025-03-19 09:23:24 -04:00
parent 361da275e5 74c1807f6c
commit 782f9feaa9
2 changed files with 28 additions and 13 deletions
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arch/x86/include/asm/kvm_host.h
+1
View File
@@ -1056,6 +1056,7 @@ struct kvm_vcpu_arch {
/* Protected Guests */
bool guest_state_protected;
bool guest_tsc_protected;
/*
* Set when PDPTS were loaded directly by the userspace without
arch/x86/kvm/x86.c
+27 -13
View File
@@ -2574,6 +2574,9 @@ EXPORT_SYMBOL_GPL(kvm_calc_nested_tsc_multiplier);
static void kvm_vcpu_write_tsc_offset(struct kvm_vcpu *vcpu, u64 l1_offset)
{
if (vcpu->arch.guest_tsc_protected)
return;
trace_kvm_write_tsc_offset(vcpu->vcpu_id,
vcpu->arch.l1_tsc_offset,
l1_offset);
@@ -2631,12 +2634,18 @@ static inline bool kvm_check_tsc_unstable(void)
* participates in.
*/
static void __kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 offset, u64 tsc,
u64 ns, bool matched)
u64 ns, bool matched, bool user_set_tsc)
{
struct kvm *kvm = vcpu->kvm;
lockdep_assert_held(&kvm->arch.tsc_write_lock);
if (vcpu->arch.guest_tsc_protected)
return;
if (user_set_tsc)
vcpu->kvm->arch.user_set_tsc = true;
/*
* We also track th most recent recorded KHZ, write and time to
* allow the matching interval to be extended at each write.
@@ -2722,8 +2731,6 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 *user_value)
}
}
if (user_value)
kvm->arch.user_set_tsc = true;
/*
* For a reliable TSC, we can match TSC offsets, and for an unstable
@@ -2743,7 +2750,7 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 *user_value)
matched = true;
}
__kvm_synchronize_tsc(vcpu, offset, data, ns, matched);
__kvm_synchronize_tsc(vcpu, offset, data, ns, matched, !!user_value);
raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
}
@@ -3923,7 +3930,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_IA32_TSC:
if (msr_info->host_initiated) {
kvm_synchronize_tsc(vcpu, &data);
} else {
} else if (!vcpu->arch.guest_tsc_protected) {
u64 adj = kvm_compute_l1_tsc_offset(vcpu, data) - vcpu->arch.l1_tsc_offset;
adjust_tsc_offset_guest(vcpu, adj);
vcpu->arch.ia32_tsc_adjust_msr += adj;
@@ -4590,6 +4597,11 @@ static bool kvm_is_vm_type_supported(unsigned long type)
return type < 32 && (kvm_caps.supported_vm_types & BIT(type));
}
static inline u32 kvm_sync_valid_fields(struct kvm *kvm)
{
return kvm && kvm->arch.has_protected_state ? 0 : KVM_SYNC_X86_VALID_FIELDS;
}
int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
{
int r = 0;
@@ -4698,7 +4710,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
break;
#endif
case KVM_CAP_SYNC_REGS:
r = KVM_SYNC_X86_VALID_FIELDS;
r = kvm_sync_valid_fields(kvm);
break;
case KVM_CAP_ADJUST_CLOCK:
r = KVM_CLOCK_VALID_FLAGS;
@@ -5003,7 +5015,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
u64 offset = kvm_compute_l1_tsc_offset(vcpu,
vcpu->arch.last_guest_tsc);
kvm_vcpu_write_tsc_offset(vcpu, offset);
vcpu->arch.tsc_catchup = 1;
if (!vcpu->arch.guest_tsc_protected)
vcpu->arch.tsc_catchup = 1;
}
if (kvm_lapic_hv_timer_in_use(vcpu))
@@ -5742,8 +5755,7 @@ static int kvm_arch_tsc_set_attr(struct kvm_vcpu *vcpu,
tsc = kvm_scale_tsc(rdtsc(), vcpu->arch.l1_tsc_scaling_ratio) + offset;
ns = get_kvmclock_base_ns();
kvm->arch.user_set_tsc = true;
__kvm_synchronize_tsc(vcpu, offset, tsc, ns, matched);
__kvm_synchronize_tsc(vcpu, offset, tsc, ns, matched, true);
raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
r = 0;
@@ -11480,6 +11492,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
{
struct kvm_queued_exception *ex = &vcpu->arch.exception;
struct kvm_run *kvm_run = vcpu->run;
u32 sync_valid_fields;
int r;
r = kvm_mmu_post_init_vm(vcpu->kvm);
@@ -11525,8 +11538,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
goto out;
}
if ((kvm_run->kvm_valid_regs & ~KVM_SYNC_X86_VALID_FIELDS) ||
(kvm_run->kvm_dirty_regs & ~KVM_SYNC_X86_VALID_FIELDS)) {
sync_valid_fields = kvm_sync_valid_fields(vcpu->kvm);
if ((kvm_run->kvm_valid_regs & ~sync_valid_fields) ||
(kvm_run->kvm_dirty_regs & ~sync_valid_fields)) {
r = -EINVAL;
goto out;
}
@@ -11584,7 +11598,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
out:
kvm_put_guest_fpu(vcpu);
if (kvm_run->kvm_valid_regs)
if (kvm_run->kvm_valid_regs && likely(!vcpu->arch.guest_state_protected))
store_regs(vcpu);
post_kvm_run_save(vcpu);
kvm_vcpu_srcu_read_unlock(vcpu);
@@ -12874,7 +12888,6 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
mutex_unlock(&kvm->slots_lock);
}
kvm_destroy_vcpus(kvm);
kvm_x86_call(vm_destroy)(kvm);
kvm_free_msr_filter(srcu_dereference_check(kvm->arch.msr_filter, &kvm->srcu, 1));
kvm_pic_destroy(kvm);
kvm_ioapic_destroy(kvm);
@@ -12884,6 +12897,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
kvm_page_track_cleanup(kvm);
kvm_xen_destroy_vm(kvm);
kvm_hv_destroy_vm(kvm);
kvm_x86_call(vm_destroy)(kvm);
}
static void memslot_rmap_free(struct kvm_memory_slot *slot)