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@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/x86.c | 34 +++++++++++++++++++++++++---------
include/linux/kvm_host.h | 7 ++++++-
3 files changed, 32 insertions(+), 10 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 35f81b1..e820c63 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -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
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2eb1124..01aafc8 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -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;
@@ -5424,9 +5427,22 @@ 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);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 57d7092..1934f48 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -27,6 +27,10 @@
#include <asm/kvm_host.h>
+#ifndef KVM_MMIO_SIZE
+#define KVM_MMIO_SIZE 8
+#endif
+
/*
* vcpu->requests bit members
*/
@@ -133,7 +137,8 @@ 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
--
1.7.1
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
