Commit 99e3e30a authored by Zachary Amsden's avatar Zachary Amsden Committed by Avi Kivity
Browse files

KVM: x86: Move TSC offset writes to common code 



Also, ensure that the storing of the offset and the reading of the TSC
are never preempted by taking a spinlock.  While the lock is overkill
now, it is useful later in this patch series.

Signed-off-by: default avatarZachary Amsden <zamsden@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent f4e1b3c8

arch/x86/include/asm/kvm_host.h

+3 −0
Original line number Diff line number Diff line
@@ -395,6 +395,7 @@ struct kvm_arch { 


	unsigned long irq_sources_bitmap;

	s64 kvmclock_offset;

	spinlock_t tsc_write_lock;



	struct kvm_xen_hvm_config xen_hvm_config;
@@ -521,6 +522,8 @@ struct kvm_x86_ops { 


	bool (*has_wbinvd_exit)(void);



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



	const struct trace_print_flags *exit_reasons_str;

};

arch/x86/kvm/svm.c

+4 −2
Original line number Diff line number Diff line
@@ -915,7 +915,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id) 
	svm->vmcb_pa = page_to_pfn(page) << PAGE_SHIFT;

	svm->asid_generation = 0;

	init_vmcb(svm);

	svm_write_tsc_offset(&svm->vcpu, 0-native_read_tsc());

	kvm_write_tsc(&svm->vcpu, 0);



	err = fx_init(&svm->vcpu);

	if (err)
@@ -2581,7 +2581,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 data) 


	switch (ecx) {

	case MSR_IA32_TSC:

		svm_write_tsc_offset(vcpu, data - native_read_tsc());

		kvm_write_tsc(vcpu, data);

		break;

	case MSR_STAR:

		svm->vmcb->save.star = data;
@@ -3551,6 +3551,8 @@ static struct kvm_x86_ops svm_x86_ops = { 
	.set_supported_cpuid = svm_set_supported_cpuid,



	.has_wbinvd_exit = svm_has_wbinvd_exit,



	.write_tsc_offset = svm_write_tsc_offset,

};



static int __init svm_init(void)

arch/x86/kvm/vmx.c

+6 −7
Original line number Diff line number Diff line
@@ -1146,10 +1146,9 @@ static u64 guest_read_tsc(void) 
}



/*

 * writes 'guest_tsc' into guest's timestamp counter "register"

 * guest_tsc = host_tsc + tsc_offset ==> tsc_offset = guest_tsc - host_tsc

 * writes 'offset' into guest's timestamp counter offset register

 */

static void vmx_write_tsc_offset(u64 offset)

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

{

	vmcs_write64(TSC_OFFSET, offset);

}
@@ -1224,7 +1223,6 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data) 
{

	struct vcpu_vmx *vmx = to_vmx(vcpu);

	struct shared_msr_entry *msr;

	u64 host_tsc;

	int ret = 0;



	switch (msr_index) {
@@ -1254,8 +1252,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data) 
		vmcs_writel(GUEST_SYSENTER_ESP, data);

		break;

	case MSR_IA32_TSC:

		rdtscll(host_tsc);

		vmx_write_tsc_offset(data - host_tsc);

		kvm_write_tsc(vcpu, data);

		break;

	case MSR_IA32_CR_PAT:

		if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
@@ -2653,7 +2650,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx) 
		vmx->vcpu.arch.cr4_guest_owned_bits |= X86_CR4_PGE;

	vmcs_writel(CR4_GUEST_HOST_MASK, ~vmx->vcpu.arch.cr4_guest_owned_bits);



	vmx_write_tsc_offset(0-native_read_tsc());

	kvm_write_tsc(&vmx->vcpu, 0);



	return 0;

}
@@ -4348,6 +4345,8 @@ static struct kvm_x86_ops vmx_x86_ops = { 
	.set_supported_cpuid = vmx_set_supported_cpuid,



	.has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,



	.write_tsc_offset = vmx_write_tsc_offset,

};



static int __init vmx_init(void)

arch/x86/kvm/x86.c

+18 −0
Original line number Diff line number Diff line
@@ -895,6 +895,22 @@ static void kvm_set_time_scale(uint32_t tsc_khz, struct pvclock_vcpu_time_info * 


static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz);



void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)

{

	struct kvm *kvm = vcpu->kvm;

	u64 offset;

	unsigned long flags;



	spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags);

	offset = data - native_read_tsc();

	kvm_x86_ops->write_tsc_offset(vcpu, offset);

	spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);



	/* Reset of TSC must disable overshoot protection below */

	vcpu->arch.hv_clock.tsc_timestamp = 0;

}

EXPORT_SYMBOL_GPL(kvm_write_tsc);



static void kvm_write_guest_time(struct kvm_vcpu *v)

{

	struct timespec ts;
@@ -5495,6 +5511,8 @@ struct kvm *kvm_arch_create_vm(void) 
	/* Reserve bit 0 of irq_sources_bitmap for userspace irq source */

	set_bit(KVM_USERSPACE_IRQ_SOURCE_ID, &kvm->arch.irq_sources_bitmap);



	spin_lock_init(&kvm->arch.tsc_write_lock);



	return kvm;

}

arch/x86/kvm/x86.h

+2 −0
Original line number Diff line number Diff line
@@ -68,4 +68,6 @@ static inline int is_paging(struct kvm_vcpu *vcpu) 
void kvm_before_handle_nmi(struct kvm_vcpu *vcpu);

void kvm_after_handle_nmi(struct kvm_vcpu *vcpu);



void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data);



#endif

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