summaryrefslogtreecommitdiff
path: root/arch/x86/kvm/vmx.c
diff options
context:
space:
mode:
authorPaolo Bonzini <pbonzini@redhat.com>2016-11-01 02:39:48 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2016-11-02 22:03:07 +0300
commitea26e4ec08d4727e3a9e48a6b74695861effcbd9 (patch)
treebe3ae8868bd0e93e6029cfd9ce0512fe69dc39ab /arch/x86/kvm/vmx.c
parentbd768e146624cbec7122ed15dead8daa137d909d (diff)
downloadlinux-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.c39
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,