[Devel,RHEL7,COMMIT] ms/KVM: x86: drop TSC offsetting kvm_x86_ops to fix KVM_GET/SET_CLOCK

Submitted by Konstantin Khorenko on Nov. 16, 2016, 12:46 p.m.

Details

Message ID 201611161246.uAGCk5aC013931@finist_cl7.x64_64.work.ct
State New
Series "add tsc_scale and fix VM pause/resume"
Headers show

Commit Message

Konstantin Khorenko Nov. 16, 2016, 12:46 p.m.
The commit is pushed to "branch-rh7-3.10.0-327.36.1.vz7.19.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.36.1.vz7.19.9
------>
commit 4e92c1145557efd8aeb0a425b1809e65327de540
Author: Paolo Bonzini <pbonzini@redhat.com>
Date:   Wed Nov 16 16:46:04 2016 +0400

    ms/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>
    
    (cherry-picked from commit ea26e4ec08d4727e3a9e48a6b74695861effcbd9)
    modifications to hyperv.c added
    fix #PSBM-54338
    Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
    Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
---
 arch/x86/include/asm/kvm_host.h |  3 ---
 arch/x86/kvm/hyperv.c           |  2 +-
 arch/x86/kvm/svm.c              | 23 -----------------------
 arch/x86/kvm/vmx.c              | 39 +++------------------------------------
 arch/x86/kvm/x86.c              |  8 ++++----
 5 files changed, 8 insertions(+), 67 deletions(-)

Patch hide | download patch | download mbox

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index aa86551..2348a55 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -821,7 +821,6 @@  struct kvm_x86_ops {
 	int (*get_lpage_level)(void);
 	bool (*rdtscp_supported)(void);
 	bool (*invpcid_supported)(void);
-	void (*adjust_tsc_offset_guest)(struct kvm_vcpu *vcpu, s64 adjustment);
 
 	void (*set_tdp_cr3)(struct kvm_vcpu *vcpu, unsigned long cr3);
 
@@ -831,8 +830,6 @@  struct kvm_x86_ops {
 
 	void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);
 
-	u64 (*read_l1_tsc)(struct kvm_vcpu *vcpu, u64 host_tsc);
-
 	void (*get_exit_info)(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2);
 
 	int (*check_intercept)(struct kvm_vcpu *vcpu,
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index b5ebcaf..9a5df5c 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -398,7 +398,7 @@  static u64 get_time_ref_counter(struct kvm *kvm)
 		return div_u64(get_kvmclock_ns(kvm), 100);
 
 	vcpu = kvm_get_vcpu(kvm, 0);
-	tsc = kvm_x86_ops->read_l1_tsc(vcpu, native_read_tsc());
+	tsc = kvm_read_l1_tsc(vcpu, native_read_tsc());
 	return mul_u64_u64_shr(tsc, hv->tsc_ref.tsc_scale, 64)
 		+ hv->tsc_ref.tsc_offset;
 }
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 9021e79..3e51a1f 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -975,21 +975,6 @@  static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
 	mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
 }
 
-static void svm_adjust_tsc_offset_guest(struct kvm_vcpu *vcpu, s64 adjustment)
-{
-	struct vcpu_svm *svm = to_svm(vcpu);
-
-	svm->vmcb->control.tsc_offset += adjustment;
-	if (is_guest_mode(vcpu))
-		svm->nested.hsave->control.tsc_offset += adjustment;
-	else
-		trace_kvm_write_tsc_offset(vcpu->vcpu_id,
-				     svm->vmcb->control.tsc_offset - adjustment,
-				     svm->vmcb->control.tsc_offset);
-
-	mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
-}
-
 static void init_vmcb(struct vcpu_svm *svm)
 {
 	struct vmcb_control_area *control = &svm->vmcb->control;
@@ -2961,12 +2946,6 @@  static int cr8_write_interception(struct vcpu_svm *svm)
 	return 0;
 }
 
-static u64 svm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
-{
-	struct vmcb *vmcb = get_host_vmcb(to_svm(vcpu));
-	return vmcb->control.tsc_offset + host_tsc;
-}
-
 static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
@@ -4341,8 +4320,6 @@  static struct kvm_x86_ops svm_x86_ops = {
 	.has_wbinvd_exit = svm_has_wbinvd_exit,
 
 	.write_tsc_offset = svm_write_tsc_offset,
-	.adjust_tsc_offset_guest = svm_adjust_tsc_offset_guest,
-	.read_l1_tsc = svm_read_l1_tsc,
 
 	.set_tdp_cr3 = set_tdp_cr3,
 
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 45007f1..6497232 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -396,7 +396,6 @@  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;
 	/* L2 must run next, and mustn't decide to exit to L1. */
 	bool nested_run_pending;
 	/*
@@ -2189,20 +2188,6 @@  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)
@@ -2215,7 +2200,6 @@  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 +
@@ -2228,19 +2212,6 @@  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);
@@ -8924,9 +8895,9 @@  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 + vmcs12->tsc_offset);
 
 	if (enable_vpid) {
 		/*
@@ -9138,8 +9109,6 @@  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);
 
@@ -9651,7 +9620,7 @@  static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 	load_vmcs12_host_state(vcpu, vmcs12);
 
 	/* Update TSC_OFFSET if TSC was changed while L2 ran */
-	vmcs_write64(TSC_OFFSET, vmx->nested.vmcs01_tsc_offset);
+	vmcs_write64(TSC_OFFSET, vcpu->arch.tsc_offset);
 
 	/* This is needed for same reason as it was needed in prepare_vmcs02 */
 	vmx->host_rsp = 0;
@@ -9851,8 +9820,6 @@  static struct kvm_x86_ops vmx_x86_ops = {
 	.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,
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5ec55b1..ea058a2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1381,7 +1381,7 @@  static u64 kvm_compute_tsc_offset(struct kvm_vcpu *vcpu, u64 target_tsc)
 
 u64 kvm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
 {
-	return kvm_x86_ops->read_l1_tsc(vcpu, kvm_scale_tsc(vcpu, host_tsc));
+	return vcpu->arch.tsc_offset + kvm_scale_tsc(vcpu, host_tsc);
 }
 EXPORT_SYMBOL_GPL(kvm_read_l1_tsc);
 
@@ -1519,7 +1519,7 @@  EXPORT_SYMBOL_GPL(kvm_write_tsc);
 static inline void adjust_tsc_offset_guest(struct kvm_vcpu *vcpu,
 					   s64 adjustment)
 {
-	kvm_x86_ops->adjust_tsc_offset_guest(vcpu, adjustment);
+	kvm_vcpu_write_tsc_offset(vcpu, vcpu->arch.tsc_offset + adjustment);
 }
 
 static inline void adjust_tsc_offset_host(struct kvm_vcpu *vcpu, s64 adjustment)
@@ -1527,7 +1527,7 @@  static inline void adjust_tsc_offset_host(struct kvm_vcpu *vcpu, s64 adjustment)
 	if (vcpu->arch.tsc_scaling_ratio != kvm_default_tsc_scaling_ratio)
 		WARN_ON(adjustment < 0);
 	adjustment = kvm_scale_tsc(vcpu, (u64) adjustment);
-	kvm_x86_ops->adjust_tsc_offset_guest(vcpu, adjustment);
+	adjust_tsc_offset_guest(vcpu, adjustment);
 }
 
 #ifdef CONFIG_X86_64
@@ -1709,7 +1709,7 @@  static u64 __get_kvmclock_ns(struct kvm *kvm)
 	u8 flags;
 
 	if (vcpu->arch.hv_clock.flags & PVCLOCK_TSC_STABLE_BIT) {
-		u64 tsc = kvm_x86_ops->read_l1_tsc(vcpu, native_read_tsc());
+		u64 tsc = kvm_read_l1_tsc(vcpu, native_read_tsc());
 		__pvclock_read_cycles(&vcpu->arch.hv_clock, &ns, &flags, tsc);
 	} else {
 		ns = ktime_to_ns(ktime_get_boottime()) + ka->kvmclock_offset;