diff options
author | Paolo Bonzini <pbonzini@redhat.com> | 2016-11-01 02:39:48 +0300 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-11-02 22:03:07 +0300 |
commit | ea26e4ec08d4727e3a9e48a6b74695861effcbd9 (patch) | |
tree | be3ae8868bd0e93e6029cfd9ce0512fe69dc39ab /arch/x86/kvm/vmx.c | |
parent | bd768e146624cbec7122ed15dead8daa137d909d (diff) | |
download | linux-ea26e4ec08d4727e3a9e48a6b74695861effcbd9.tar.xz |
KVM: x86: drop TSC offsetting kvm_x86_ops to fix KVM_GET/SET_CLOCK
Since commit a545ab6a0085 ("kvm: x86: add tsc_offset field to struct
kvm_vcpu_arch", 2016-09-07) the offset between host and L1 TSC is
cached and need not be fished out of the VMCS or VMCB. This means
that we can implement adjust_tsc_offset_guest and read_l1_tsc
entirely in generic code. The simplification is particularly
significant for VMX code, where vmx->nested.vmcs01_tsc_offset
was duplicating what is now in vcpu->arch.tsc_offset. Therefore
the vmcs01_tsc_offset can be dropped completely.
More importantly, this fixes KVM_GET_CLOCK/KVM_SET_CLOCK
which, after commit 108b249c453d ("KVM: x86: introduce get_kvmclock_ns",
2016-09-01) called read_l1_tsc while the VMCS was not loaded.
It thus returned bogus values on Intel CPUs.
Fixes: 108b249c453dd7132599ab6dc7e435a7036c193f
Reported-by: Roman Kagan <rkagan@virtuozzo.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/vmx.c')
-rw-r--r-- | arch/x86/kvm/vmx.c | 39 |
1 files changed, 3 insertions, 36 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 74a4df993a51..754c3a7f444a 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -421,7 +421,6 @@ struct nested_vmx { /* vmcs02_list cache of VMCSs recently used to run L2 guests */ struct list_head vmcs02_pool; int vmcs02_num; - u64 vmcs01_tsc_offset; bool change_vmcs01_virtual_x2apic_mode; /* L2 must run next, and mustn't decide to exit to L1. */ bool nested_run_pending; @@ -2605,20 +2604,6 @@ static u64 guest_read_tsc(struct kvm_vcpu *vcpu) } /* - * Like guest_read_tsc, but always returns L1's notion of the timestamp - * counter, even if a nested guest (L2) is currently running. - */ -static u64 vmx_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc) -{ - u64 tsc_offset; - - tsc_offset = is_guest_mode(vcpu) ? - to_vmx(vcpu)->nested.vmcs01_tsc_offset : - vmcs_read64(TSC_OFFSET); - return host_tsc + tsc_offset; -} - -/* * writes 'offset' into guest's timestamp counter offset register */ static void vmx_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset) @@ -2631,7 +2616,6 @@ static void vmx_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset) * to the newly set TSC to get L2's TSC. */ struct vmcs12 *vmcs12; - to_vmx(vcpu)->nested.vmcs01_tsc_offset = offset; /* recalculate vmcs02.TSC_OFFSET: */ vmcs12 = get_vmcs12(vcpu); vmcs_write64(TSC_OFFSET, offset + @@ -2644,19 +2628,6 @@ static void vmx_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset) } } -static void vmx_adjust_tsc_offset_guest(struct kvm_vcpu *vcpu, s64 adjustment) -{ - u64 offset = vmcs_read64(TSC_OFFSET); - - vmcs_write64(TSC_OFFSET, offset + adjustment); - if (is_guest_mode(vcpu)) { - /* Even when running L2, the adjustment needs to apply to L1 */ - to_vmx(vcpu)->nested.vmcs01_tsc_offset += adjustment; - } else - trace_kvm_write_tsc_offset(vcpu->vcpu_id, offset, - offset + adjustment); -} - static bool guest_cpuid_has_vmx(struct kvm_vcpu *vcpu) { struct kvm_cpuid_entry2 *best = kvm_find_cpuid_entry(vcpu, 1, 0); @@ -10061,9 +10032,9 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING) vmcs_write64(TSC_OFFSET, - vmx->nested.vmcs01_tsc_offset + vmcs12->tsc_offset); + vcpu->arch.tsc_offset + vmcs12->tsc_offset); else - vmcs_write64(TSC_OFFSET, vmx->nested.vmcs01_tsc_offset); + vmcs_write64(TSC_OFFSET, vcpu->arch.tsc_offset); if (kvm_has_tsc_control) decache_tsc_multiplier(vmx); @@ -10293,8 +10264,6 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch) enter_guest_mode(vcpu); - vmx->nested.vmcs01_tsc_offset = vmcs_read64(TSC_OFFSET); - if (!(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS)) vmx->nested.vmcs01_debugctl = vmcs_read64(GUEST_IA32_DEBUGCTL); @@ -10818,7 +10787,7 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, load_vmcs12_host_state(vcpu, vmcs12); /* Update any VMCS fields that might have changed while L2 ran */ - vmcs_write64(TSC_OFFSET, vmx->nested.vmcs01_tsc_offset); + vmcs_write64(TSC_OFFSET, vcpu->arch.tsc_offset); if (vmx->hv_deadline_tsc == -1) vmcs_clear_bits(PIN_BASED_VM_EXEC_CONTROL, PIN_BASED_VMX_PREEMPTION_TIMER); @@ -11339,8 +11308,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = { .has_wbinvd_exit = cpu_has_vmx_wbinvd_exit, .write_tsc_offset = vmx_write_tsc_offset, - .adjust_tsc_offset_guest = vmx_adjust_tsc_offset_guest, - .read_l1_tsc = vmx_read_l1_tsc, .set_tdp_cr3 = vmx_set_cr3, |