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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: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2010-01-20 12:01:20 +02:00
parent 5287f194bf
commit cef4dea07f
3 changed files with 32 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/kvm_host.h
View File

@ -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

34
arch/x86/kvm/x86.c
View File

@ -3833,8 +3833,10 @@ mmio:
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 @@ mmio:
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 @@ restart:
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) {
memcpy(vcpu->mmio_data, run->mmio.data, 8);
vcpu->mmio_read_completed = 1;
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->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
r = emulate_instruction(vcpu, EMULTYPE_NO_DECODE);

7
include/linux/kvm_host.h
View File

@ -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