Commit 69d413cf authored by David Woodhouse's avatar David Woodhouse Committed by Paolo Bonzini
Browse files

KVM: x86/xen: Use gfn_to_pfn_cache for vcpu_time_info 



This switches the final pvclock to kvm_setup_pvclock_pfncache() and now
the old kvm_setup_pvclock_page() can be removed.

Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-7-dwmw2@infradead.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 7caf9571

arch/x86/include/asm/kvm_host.h

+1 −2
Original line number Diff line number Diff line
@@ -606,9 +606,8 @@ struct kvm_vcpu_hv { 
struct kvm_vcpu_xen {

	u64 hypercall_rip;

	u32 current_runstate;

	bool vcpu_time_info_set;

	struct gfn_to_pfn_cache vcpu_info_cache;

	struct gfn_to_hva_cache vcpu_time_info_cache;

	struct gfn_to_pfn_cache vcpu_time_info_cache;

	struct gfn_to_pfn_cache runstate_cache;

	u64 last_steal;

	u64 runstate_entry_time;

arch/x86/kvm/x86.c

+2 −61
Original line number Diff line number Diff line
@@ -3011,65 +3011,6 @@ static void kvm_setup_guest_pvclock(struct kvm_vcpu *v, 
	trace_kvm_pvclock_update(v->vcpu_id, &vcpu->hv_clock);

}



static void kvm_setup_pvclock_page(struct kvm_vcpu *v,

				   struct gfn_to_hva_cache *cache,

				   unsigned int offset)

{

	struct kvm_vcpu_arch *vcpu = &v->arch;

	struct pvclock_vcpu_time_info guest_hv_clock;



	if (unlikely(kvm_read_guest_offset_cached(v->kvm, cache,

		&guest_hv_clock, offset, sizeof(guest_hv_clock))))

		return;



	/* This VCPU is paused, but it's legal for a guest to read another

	 * VCPU's kvmclock, so we really have to follow the specification where

	 * it says that version is odd if data is being modified, and even after

	 * it is consistent.

	 *

	 * Version field updates must be kept separate.  This is because

	 * kvm_write_guest_cached might use a "rep movs" instruction, and

	 * writes within a string instruction are weakly ordered.  So there

	 * are three writes overall.

	 *

	 * As a small optimization, only write the version field in the first

	 * and third write.  The vcpu->pv_time cache is still valid, because the

	 * version field is the first in the struct.

	 */

	BUILD_BUG_ON(offsetof(struct pvclock_vcpu_time_info, version) != 0);



	if (guest_hv_clock.version & 1)

		++guest_hv_clock.version;  /* first time write, random junk */



	vcpu->hv_clock.version = guest_hv_clock.version + 1;

	kvm_write_guest_offset_cached(v->kvm, cache,

				      &vcpu->hv_clock, offset,

				      sizeof(vcpu->hv_clock.version));



	smp_wmb();



	/* retain PVCLOCK_GUEST_STOPPED if set in guest copy */

	vcpu->hv_clock.flags |= (guest_hv_clock.flags & PVCLOCK_GUEST_STOPPED);



	if (vcpu->pvclock_set_guest_stopped_request) {

		vcpu->hv_clock.flags |= PVCLOCK_GUEST_STOPPED;

		vcpu->pvclock_set_guest_stopped_request = false;

	}



	trace_kvm_pvclock_update(v->vcpu_id, &vcpu->hv_clock);



	kvm_write_guest_offset_cached(v->kvm, cache,

				      &vcpu->hv_clock, offset,

				      sizeof(vcpu->hv_clock));



	smp_wmb();



	vcpu->hv_clock.version++;

	kvm_write_guest_offset_cached(v->kvm, cache,

				     &vcpu->hv_clock, offset,

				     sizeof(vcpu->hv_clock.version));

}



static int kvm_guest_time_update(struct kvm_vcpu *v)

{

	unsigned long flags, tgt_tsc_khz;
@@ -3161,8 +3102,8 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) 
	if (vcpu->xen.vcpu_info_cache.active)

		kvm_setup_guest_pvclock(v, &vcpu->xen.vcpu_info_cache,

					offsetof(struct compat_vcpu_info, time));

	if (vcpu->xen.vcpu_time_info_set)

		kvm_setup_pvclock_page(v, &vcpu->xen.vcpu_time_info_cache, 0);

	if (vcpu->xen.vcpu_time_info_cache.active)

		kvm_setup_guest_pvclock(v, &vcpu->xen.vcpu_time_info_cache, 0);

	if (!v->vcpu_idx)

		kvm_hv_setup_tsc_page(v->kvm, &vcpu->hv_clock);

	return 0;

arch/x86/kvm/xen.c

+8 −13
Original line number Diff line number Diff line
@@ -463,25 +463,18 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) 


	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO:

		if (data->u.gpa == GPA_INVALID) {

			vcpu->arch.xen.vcpu_time_info_set = false;

			kvm_gfn_to_pfn_cache_destroy(vcpu->kvm,

						     &vcpu->arch.xen.vcpu_time_info_cache);

			r = 0;

			break;

		}



		/* It must fit within a single page */

		if ((data->u.gpa & ~PAGE_MASK) + sizeof(struct pvclock_vcpu_time_info) > PAGE_SIZE) {

			r = -EINVAL;

			break;

		}



		r = kvm_gfn_to_hva_cache_init(vcpu->kvm,

		r = kvm_gfn_to_pfn_cache_init(vcpu->kvm,

					      &vcpu->arch.xen.vcpu_time_info_cache,

					      data->u.gpa,

					      NULL, KVM_HOST_USES_PFN, data->u.gpa,

					      sizeof(struct pvclock_vcpu_time_info));

		if (!r) {

			vcpu->arch.xen.vcpu_time_info_set = true;

		if (!r)

			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);

		}

		break;



	case KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR:
@@ -622,7 +615,7 @@ int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) 
		break;



	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO:

		if (vcpu->arch.xen.vcpu_time_info_set)

		if (vcpu->arch.xen.vcpu_time_info_cache.active)

			data->u.gpa = vcpu->arch.xen.vcpu_time_info_cache.gpa;

		else

			data->u.gpa = GPA_INVALID;
@@ -1066,4 +1059,6 @@ void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu) 
				     &vcpu->arch.xen.runstate_cache);

	kvm_gfn_to_pfn_cache_destroy(vcpu->kvm,

				     &vcpu->arch.xen.vcpu_info_cache);

	kvm_gfn_to_pfn_cache_destroy(vcpu->kvm,

				     &vcpu->arch.xen.vcpu_time_info_cache);

}