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Commit 716d51ab authored by Gleb Natapov's avatar Gleb Natapov Committed by Avi Kivity
Browse files

KVM: Provide userspace IO exit completion callback 



Current code assumes that IO exit was due to instruction emulation
and handles execution back to emulator directly. This patch adds new
userspace IO exit completion callback that can be set by any other code
that caused IO exit to userspace.

Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 3b4dc3a0

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -414,6 +414,7 @@ struct kvm_vcpu_arch { 
	struct x86_emulate_ctxt emulate_ctxt;

	bool emulate_regs_need_sync_to_vcpu;

	bool emulate_regs_need_sync_from_vcpu;

	int (*complete_userspace_io)(struct kvm_vcpu *vcpu);



	gpa_t time;

	struct pvclock_vcpu_time_info hv_clock;

arch/x86/kvm/x86.c

+56 −37
Original line number Diff line number Diff line
@@ -4544,6 +4544,9 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt, 
	return true;

}



static int complete_emulated_mmio(struct kvm_vcpu *vcpu);

static int complete_emulated_pio(struct kvm_vcpu *vcpu);



int x86_emulate_instruction(struct kvm_vcpu *vcpu,

			    unsigned long cr2,

			    int emulation_type,
@@ -4614,13 +4617,16 @@ restart: 
	} else if (vcpu->arch.pio.count) {

		if (!vcpu->arch.pio.in)

			vcpu->arch.pio.count = 0;

		else

		else {

			writeback = false;

			vcpu->arch.complete_userspace_io = complete_emulated_pio;

		}

		r = EMULATE_DO_MMIO;

	} else if (vcpu->mmio_needed) {

		if (!vcpu->mmio_is_write)

			writeback = false;

		r = EMULATE_DO_MMIO;

		vcpu->arch.complete_userspace_io = complete_emulated_mmio;

	} else if (r == EMULATION_RESTART)

		goto restart;

	else
@@ -5476,6 +5482,24 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) 
	return r;

}



static inline int complete_emulated_io(struct kvm_vcpu *vcpu)

{

	int r;

	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);

	r = emulate_instruction(vcpu, EMULTYPE_NO_DECODE);

	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);

	if (r != EMULATE_DONE)

		return 0;

	return 1;

}



static int complete_emulated_pio(struct kvm_vcpu *vcpu)

{

	BUG_ON(!vcpu->arch.pio.count);



	return complete_emulated_io(vcpu);

}



/*

 * Implements the following, as a state machine:

 *
@@ -5492,16 +5516,13 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) 
 *      copy data

 *      exit

 */

static int complete_mmio(struct kvm_vcpu *vcpu)

static int complete_emulated_mmio(struct kvm_vcpu *vcpu)

{

	struct kvm_run *run = vcpu->run;

	struct kvm_mmio_fragment *frag;

	int r;



	if (!(vcpu->arch.pio.count || vcpu->mmio_needed))

		return 1;

	BUG_ON(!vcpu->mmio_needed);



	if (vcpu->mmio_needed) {

	/* Complete previous fragment */

	frag = &vcpu->mmio_fragments[vcpu->mmio_cur_fragment++];

	if (!vcpu->mmio_is_write)
@@ -5511,7 +5532,7 @@ static int complete_mmio(struct kvm_vcpu *vcpu) 
		if (vcpu->mmio_is_write)

			return 1;

		vcpu->mmio_read_completed = 1;

			goto done;

		return complete_emulated_io(vcpu);

	}

	/* Initiate next fragment */

	++frag;
@@ -5521,18 +5542,11 @@ static int complete_mmio(struct kvm_vcpu *vcpu) 
		memcpy(run->mmio.data, frag->data, frag->len);

	run->mmio.len = frag->len;

	run->mmio.is_write = vcpu->mmio_is_write;

	vcpu->arch.complete_userspace_io = complete_emulated_mmio;

	return 0;



	}

done:

	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);

	r = emulate_instruction(vcpu, EMULTYPE_NO_DECODE);

	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);

	if (r != EMULATE_DONE)

		return 0;

	return 1;

}





int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)

{

	int r;
@@ -5559,9 +5573,14 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
		}

	}



	r = complete_mmio(vcpu);

	if (unlikely(vcpu->arch.complete_userspace_io)) {

		int (*cui)(struct kvm_vcpu *) = vcpu->arch.complete_userspace_io;

		vcpu->arch.complete_userspace_io = NULL;

		r = cui(vcpu);

		if (r <= 0)

			goto out;

	} else

		WARN_ON(vcpu->arch.pio.count || vcpu->mmio_needed);



	r = __vcpu_run(vcpu);