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Commit cef4dea0 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: 16-byte mmio support 



Since sse instructions can issue 16-byte mmios, we need to support them.  We
can't increase the kvm_run mmio buffer size to 16 bytes without breaking
compatibility, so instead we break the large mmios into two smaller 8-byte
ones.  Since the bus is 64-bit we aren't breaking any atomicity guarantees.

Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 5287f194

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#define KVM_MEMORY_SLOTS 32

/* memory slots that does not exposed to userspace */

#define KVM_PRIVATE_MEM_SLOTS 4

#define KVM_MMIO_SIZE 16



#define KVM_PIO_PAGE_OFFSET 1

#define KVM_COALESCED_MMIO_PAGE_OFFSET 2

arch/x86/kvm/x86.c

+25 −9
Original line number Diff line number Diff line
@@ -3833,8 +3833,10 @@ static int emulator_read_emulated(unsigned long addr, 
	vcpu->mmio_needed = 1;

	vcpu->run->exit_reason = KVM_EXIT_MMIO;

	vcpu->run->mmio.phys_addr = vcpu->mmio_phys_addr = gpa;

	vcpu->run->mmio.len = vcpu->mmio_size = bytes;

	vcpu->mmio_size = bytes;

	vcpu->run->mmio.len = min(vcpu->mmio_size, 8);

	vcpu->run->mmio.is_write = vcpu->mmio_is_write = 0;

	vcpu->mmio_index = 0;



	return X86EMUL_IO_NEEDED;

}
@@ -3886,11 +3888,14 @@ static int emulator_write_emulated_onepage(unsigned long addr, 
	val += handled;



	vcpu->mmio_needed = 1;

	memcpy(vcpu->mmio_data, val, bytes);

	vcpu->run->exit_reason = KVM_EXIT_MMIO;

	vcpu->run->mmio.phys_addr = vcpu->mmio_phys_addr = gpa;

	vcpu->run->mmio.len = vcpu->mmio_size = bytes;

	vcpu->mmio_size = bytes;

	vcpu->run->mmio.len = min(vcpu->mmio_size, 8);

	vcpu->run->mmio.is_write = vcpu->mmio_is_write = 1;

	memcpy(vcpu->run->mmio.data, val, bytes);

	memcpy(vcpu->run->mmio.data, vcpu->mmio_data, 8);

	vcpu->mmio_index = 0;



	return X86EMUL_CONTINUE;

}
@@ -4498,11 +4503,9 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, 
		if (!vcpu->arch.pio.in)

			vcpu->arch.pio.count = 0;

		r = EMULATE_DO_MMIO;

	} else if (vcpu->mmio_needed) {

		if (vcpu->mmio_is_write)

			vcpu->mmio_needed = 0;

	} else if (vcpu->mmio_needed)

		r = EMULATE_DO_MMIO;

	} else if (r == EMULATION_RESTART)

	else if (r == EMULATION_RESTART)

		goto restart;

	else

		r = EMULATE_DONE;
@@ -5450,9 +5453,22 @@ static int complete_mmio(struct kvm_vcpu *vcpu) 
		return 1;



	if (vcpu->mmio_needed) {

		vcpu->mmio_needed = 0;

		if (!vcpu->mmio_is_write)

			memcpy(vcpu->mmio_data, run->mmio.data, 8);

		vcpu->mmio_index += 8;

		if (vcpu->mmio_index < vcpu->mmio_size) {

			run->exit_reason = KVM_EXIT_MMIO;

			run->mmio.phys_addr = vcpu->mmio_phys_addr + vcpu->mmio_index;

			memcpy(run->mmio.data, vcpu->mmio_data + vcpu->mmio_index, 8);

			run->mmio.len = min(vcpu->mmio_size - vcpu->mmio_index, 8);

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

			vcpu->mmio_needed = 1;

			return 0;

		}

		if (vcpu->mmio_is_write)

			return 1;

		vcpu->mmio_read_completed = 1;

		vcpu->mmio_needed = 0;

	}

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

	r = emulate_instruction(vcpu, EMULTYPE_NO_DECODE);

include/linux/kvm_host.h

+6 −1
Original line number Diff line number Diff line
@@ -27,6 +27,10 @@ 


#include <asm/kvm_host.h>



#ifndef KVM_MMIO_SIZE

#define KVM_MMIO_SIZE 8

#endif



/*

 * vcpu->requests bit members

 */
@@ -132,7 +136,8 @@ struct kvm_vcpu { 
	int mmio_read_completed;

	int mmio_is_write;

	int mmio_size;

	unsigned char mmio_data[8];

	int mmio_index;

	unsigned char mmio_data[KVM_MMIO_SIZE];

	gpa_t mmio_phys_addr;

#endif