Commit 95e16b47 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: SEV-ES: go over the sev_pio_data buffer in multiple passes if needed 



The PIO scratch buffer is larger than a single page, and therefore
it is not possible to copy it in a single step to vcpu->arch/pio_data.
Bound each call to emulator_pio_in/out to a single page; keep
track of how many I/O operations are left in vcpu->arch.sev_pio_count,
so that the operation can be restarted in the complete_userspace_io
callback.

For OUT, this means that the previous kvm_sev_es_outs implementation
becomes an iterator of the loop, and we can consume the sev_pio_data
buffer before leaving to userspace.

For IN, instead, consuming the buffer and decreasing sev_pio_count
is always done in the complete_userspace_io callback, because that
is when the memcpy is done into sev_pio_data.

Cc: stable@vger.kernel.org
Fixes: 7ed9abfe ("KVM: SVM: Support string IO operations for an SEV-ES guest")
Reported-by: default avatarFelix Wilhelm <fwilhelm@google.com>
Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4fa4b38d

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -703,6 +703,7 @@ struct kvm_vcpu_arch { 
	struct kvm_pio_request pio;

	void *pio_data;

	void *sev_pio_data;

	unsigned sev_pio_count;



	u8 event_exit_inst_len;

arch/x86/kvm/x86.c

+56 −16
Original line number Diff line number Diff line
@@ -12386,38 +12386,77 @@ int kvm_sev_es_mmio_read(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned int bytes, 
EXPORT_SYMBOL_GPL(kvm_sev_es_mmio_read);



static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size,

			   unsigned int port, unsigned int count)

			   unsigned int port);



static int complete_sev_es_emulated_outs(struct kvm_vcpu *vcpu)

{

	int ret = emulator_pio_out(vcpu, size, port,

				   vcpu->arch.sev_pio_data, count);

	int size = vcpu->arch.pio.size;

	int port = vcpu->arch.pio.port;



	vcpu->arch.pio.count = 0;

	if (vcpu->arch.sev_pio_count)

		return kvm_sev_es_outs(vcpu, size, port);

	return 1;

}



static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size,

			   unsigned int port)

{

	for (;;) {

		unsigned int count =

			min_t(unsigned int, PAGE_SIZE / size, vcpu->arch.sev_pio_count);

		int ret = emulator_pio_out(vcpu, size, port, vcpu->arch.sev_pio_data, count);



		/* memcpy done already by emulator_pio_out.  */

		vcpu->arch.sev_pio_count -= count;

		vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size;

		if (!ret)

			break;



	if (ret) {

		/* Emulation done by the kernel.  */

		return ret;

		if (!vcpu->arch.sev_pio_count)

			return 1;

	}



	vcpu->arch.pio.count = 0;

	vcpu->arch.complete_userspace_io = complete_sev_es_emulated_outs;

	return 0;

}



static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size,

			  unsigned int port);



static void advance_sev_es_emulated_ins(struct kvm_vcpu *vcpu)

{

	unsigned count = vcpu->arch.pio.count;

	complete_emulator_pio_in(vcpu, vcpu->arch.sev_pio_data);

	vcpu->arch.sev_pio_count -= count;

	vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size;

}



static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu)

{

	memcpy(vcpu->arch.sev_pio_data, vcpu->arch.pio_data,

	       vcpu->arch.pio.count * vcpu->arch.pio.size);

	vcpu->arch.pio.count = 0;

	int size = vcpu->arch.pio.size;

	int port = vcpu->arch.pio.port;



	advance_sev_es_emulated_ins(vcpu);

	if (vcpu->arch.sev_pio_count)

		return kvm_sev_es_ins(vcpu, size, port);

	return 1;

}



static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size,

			  unsigned int port, unsigned int count)

			  unsigned int port)

{

	int ret = emulator_pio_in(vcpu, size, port,

				  vcpu->arch.sev_pio_data, count);

	for (;;) {

		unsigned int count =

			min_t(unsigned int, PAGE_SIZE / size, vcpu->arch.sev_pio_count);

		if (!__emulator_pio_in(vcpu, size, port, count))

			break;



	if (ret) {

		/* Emulation done by the kernel.  */

		return ret;

		advance_sev_es_emulated_ins(vcpu);

		if (!vcpu->arch.sev_pio_count)

			return 1;

	}



	vcpu->arch.complete_userspace_io = complete_sev_es_emulated_ins;
@@ -12429,8 +12468,9 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size, 
			 int in)

{

	vcpu->arch.sev_pio_data = data;

	return in ? kvm_sev_es_ins(vcpu, size, port, count)

		  : kvm_sev_es_outs(vcpu, size, port, count);

	vcpu->arch.sev_pio_count = count;

	return in ? kvm_sev_es_ins(vcpu, size, port)

		  : kvm_sev_es_outs(vcpu, size, port);

}

EXPORT_SYMBOL_GPL(kvm_sev_es_string_io);