Commit e79f245d authored by KarimAllah Ahmed's avatar KarimAllah Ahmed Committed by Paolo Bonzini
Browse files

X86/KVM: Properly update 'tsc_offset' to represent the running guest 



Update 'tsc_offset' on vmentry/vmexit of L2 guests to ensure that it always
captures the TSC_OFFSET of the running guest whether it is the L1 or L2
guest.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: default avatarJim Mattson <jmattson@google.com>
Suggested-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarKarimAllah Ahmed <karahmed@amazon.de>
[AMD changes, fix update_ia32_tsc_adjust_msr. - Paolo]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4e1acd7b

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -1013,6 +1013,7 @@ struct kvm_x86_ops { 


	bool (*has_wbinvd_exit)(void);



	u64 (*read_l1_tsc_offset)(struct kvm_vcpu *vcpu);

	void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);



	void (*get_exit_info)(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2);

arch/x86/kvm/svm.c

+16 −1
Original line number Diff line number Diff line
@@ -1424,12 +1424,23 @@ static void init_sys_seg(struct vmcb_seg *seg, uint32_t type) 
	seg->base = 0;

}



static u64 svm_read_l1_tsc_offset(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);



	if (is_guest_mode(vcpu))

		return svm->nested.hsave->control.tsc_offset;



	return vcpu->arch.tsc_offset;

}



static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	u64 g_tsc_offset = 0;



	if (is_guest_mode(vcpu)) {

		/* Write L1's TSC offset.  */

		g_tsc_offset = svm->vmcb->control.tsc_offset -

			       svm->nested.hsave->control.tsc_offset;

		svm->nested.hsave->control.tsc_offset = offset;
@@ -3323,6 +3334,7 @@ static int nested_svm_vmexit(struct vcpu_svm *svm) 
	/* Restore the original control entries */

	copy_vmcb_control_area(vmcb, hsave);



	svm->vcpu.arch.tsc_offset = svm->vmcb->control.tsc_offset;

	kvm_clear_exception_queue(&svm->vcpu);

	kvm_clear_interrupt_queue(&svm->vcpu);
@@ -3483,10 +3495,12 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa, 
	/* We don't want to see VMMCALLs from a nested guest */

	clr_intercept(svm, INTERCEPT_VMMCALL);



	svm->vcpu.arch.tsc_offset += nested_vmcb->control.tsc_offset;

	svm->vmcb->control.tsc_offset = svm->vcpu.arch.tsc_offset;



	svm->vmcb->control.virt_ext = nested_vmcb->control.virt_ext;

	svm->vmcb->control.int_vector = nested_vmcb->control.int_vector;

	svm->vmcb->control.int_state = nested_vmcb->control.int_state;

	svm->vmcb->control.tsc_offset += nested_vmcb->control.tsc_offset;

	svm->vmcb->control.event_inj = nested_vmcb->control.event_inj;

	svm->vmcb->control.event_inj_err = nested_vmcb->control.event_inj_err;
@@ -7102,6 +7116,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = { 


	.has_wbinvd_exit = svm_has_wbinvd_exit,



	.read_l1_tsc_offset = svm_read_l1_tsc_offset,

	.write_tsc_offset = svm_write_tsc_offset,



	.set_tdp_cr3 = set_tdp_cr3,

arch/x86/kvm/vmx.c

+35 −19
Original line number Diff line number Diff line
@@ -2874,6 +2874,17 @@ static void setup_msrs(struct vcpu_vmx *vmx) 
		vmx_update_msr_bitmap(&vmx->vcpu);

}



static u64 vmx_read_l1_tsc_offset(struct kvm_vcpu *vcpu)

{

	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);



	if (is_guest_mode(vcpu) &&

	    (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING))

		return vcpu->arch.tsc_offset - vmcs12->tsc_offset;



	return vcpu->arch.tsc_offset;

}



/*

 * reads and returns guest's timestamp counter "register"

 * guest_tsc = (host_tsc * tsc multiplier) >> 48 + tsc_offset
@@ -11175,11 +11186,8 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, 
		vmcs_write64(GUEST_IA32_PAT, vmx->vcpu.arch.pat);

	}



	if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)

		vmcs_write64(TSC_OFFSET,

			vcpu->arch.tsc_offset + vmcs12->tsc_offset);

	else

	vmcs_write64(TSC_OFFSET, vcpu->arch.tsc_offset);



	if (kvm_has_tsc_control)

		decache_tsc_multiplier(vmx);
@@ -11427,6 +11435,7 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry) 
	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);

	u32 msr_entry_idx;

	u32 exit_qual;

	int r;



	enter_guest_mode(vcpu);
@@ -11436,26 +11445,21 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry) 
	vmx_switch_vmcs(vcpu, &vmx->nested.vmcs02);

	vmx_segment_cache_clear(vmx);



	if (prepare_vmcs02(vcpu, vmcs12, from_vmentry, &exit_qual)) {

		leave_guest_mode(vcpu);

		vmx_switch_vmcs(vcpu, &vmx->vmcs01);

		nested_vmx_entry_failure(vcpu, vmcs12,

					 EXIT_REASON_INVALID_STATE, exit_qual);

		return 1;

	}

	if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)

		vcpu->arch.tsc_offset += vmcs12->tsc_offset;



	r = EXIT_REASON_INVALID_STATE;

	if (prepare_vmcs02(vcpu, vmcs12, from_vmentry, &exit_qual))

		goto fail;



	nested_get_vmcs12_pages(vcpu, vmcs12);



	r = EXIT_REASON_MSR_LOAD_FAIL;

	msr_entry_idx = nested_vmx_load_msr(vcpu,

					    vmcs12->vm_entry_msr_load_addr,

					    vmcs12->vm_entry_msr_load_count);

	if (msr_entry_idx) {

		leave_guest_mode(vcpu);

		vmx_switch_vmcs(vcpu, &vmx->vmcs01);

		nested_vmx_entry_failure(vcpu, vmcs12,

				EXIT_REASON_MSR_LOAD_FAIL, msr_entry_idx);

		return 1;

	}

	if (msr_entry_idx)

		goto fail;



	/*

	 * Note no nested_vmx_succeed or nested_vmx_fail here. At this point
@@ -11464,6 +11468,14 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry) 
	 * the success flag) when L2 exits (see nested_vmx_vmexit()).

	 */

	return 0;



fail:

	if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)

		vcpu->arch.tsc_offset -= vmcs12->tsc_offset;

	leave_guest_mode(vcpu);

	vmx_switch_vmcs(vcpu, &vmx->vmcs01);

	nested_vmx_entry_failure(vcpu, vmcs12, r, exit_qual);

	return 1;

}



/*
@@ -12035,6 +12047,9 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, 


	leave_guest_mode(vcpu);



	if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)

		vcpu->arch.tsc_offset -= vmcs12->tsc_offset;



	if (likely(!vmx->fail)) {

		if (exit_reason == -1)

			sync_vmcs12(vcpu, vmcs12);
@@ -12725,6 +12740,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = { 


	.has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,



	.read_l1_tsc_offset = vmx_read_l1_tsc_offset,

	.write_tsc_offset = vmx_write_tsc_offset,



	.set_tdp_cr3 = vmx_set_cr3,

arch/x86/kvm/x86.c

+4 −2
Original line number Diff line number Diff line
@@ -1490,7 +1490,7 @@ static void kvm_track_tsc_matching(struct kvm_vcpu *vcpu) 


static void update_ia32_tsc_adjust_msr(struct kvm_vcpu *vcpu, s64 offset)

{

	u64 curr_offset = vcpu->arch.tsc_offset;

	u64 curr_offset = kvm_x86_ops->read_l1_tsc_offset(vcpu);

	vcpu->arch.ia32_tsc_adjust_msr += offset - curr_offset;

}
@@ -1532,7 +1532,9 @@ 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 vcpu->arch.tsc_offset + kvm_scale_tsc(vcpu, host_tsc);

	u64 tsc_offset = kvm_x86_ops->read_l1_tsc_offset(vcpu);



	return tsc_offset + kvm_scale_tsc(vcpu, host_tsc);

}

EXPORT_SYMBOL_GPL(kvm_read_l1_tsc);

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