arm/arm64: KVM: MMIO support for BE guest
Do the necessary byteswap when host and guest have different
views of the universe. Actually, the only case we need to take
care of is when the guest is BE. All the other cases are naturally
handled.
Also be careful about endianness when the data is being memcopy-ed
from/to the run buffer.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
index 0c25d94..4cb5a93 100644
--- a/arch/arm/kvm/mmio.c
+++ b/arch/arm/kvm/mmio.c
@@ -23,6 +23,68 @@
#include "trace.h"
+static void mmio_write_buf(char *buf, unsigned int len, unsigned long data)
+{
+ void *datap = NULL;
+ union {
+ u8 byte;
+ u16 hword;
+ u32 word;
+ u64 dword;
+ } tmp;
+
+ switch (len) {
+ case 1:
+ tmp.byte = data;
+ datap = &tmp.byte;
+ break;
+ case 2:
+ tmp.hword = data;
+ datap = &tmp.hword;
+ break;
+ case 4:
+ tmp.word = data;
+ datap = &tmp.word;
+ break;
+ case 8:
+ tmp.dword = data;
+ datap = &tmp.dword;
+ break;
+ }
+
+ memcpy(buf, datap, len);
+}
+
+static unsigned long mmio_read_buf(char *buf, unsigned int len)
+{
+ unsigned long data = 0;
+ union {
+ u16 hword;
+ u32 word;
+ u64 dword;
+ } tmp;
+
+ switch (len) {
+ case 1:
+ data = buf[0];
+ break;
+ case 2:
+ memcpy(&tmp.hword, buf, len);
+ data = tmp.hword;
+ break;
+ case 4:
+ memcpy(&tmp.word, buf, len);
+ data = tmp.word;
+ break;
+ case 8:
+ memcpy(&tmp.dword, buf, len);
+ data = tmp.dword;
+ break;
+ }
+
+ return data;
+}
+
/**
* kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
* @vcpu: The VCPU pointer
@@ -33,28 +95,27 @@
*/
int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
- unsigned long *dest;
+ unsigned long data;
unsigned int len;
int mask;
if (!run->mmio.is_write) {
- dest = vcpu_reg(vcpu, vcpu->arch.mmio_decode.rt);
- *dest = 0;
-
len = run->mmio.len;
if (len > sizeof(unsigned long))
return -EINVAL;
- memcpy(dest, run->mmio.data, len);
-
- trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
- *((u64 *)run->mmio.data));
+ data = mmio_read_buf(run->mmio.data, len);
if (vcpu->arch.mmio_decode.sign_extend &&
len < sizeof(unsigned long)) {
mask = 1U << ((len * 8) - 1);
- *dest = (*dest ^ mask) - mask;
+ data = (data ^ mask) - mask;
}
+
+ trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
+ data);
+ data = vcpu_data_host_to_guest(vcpu, data, len);
+ *vcpu_reg(vcpu, vcpu->arch.mmio_decode.rt) = data;
}
return 0;
@@ -105,6 +166,7 @@
phys_addr_t fault_ipa)
{
struct kvm_exit_mmio mmio;
+ unsigned long data;
unsigned long rt;
int ret;
@@ -125,13 +187,15 @@
}
rt = vcpu->arch.mmio_decode.rt;
+ data = vcpu_data_guest_to_host(vcpu, *vcpu_reg(vcpu, rt), mmio.len);
+
trace_kvm_mmio((mmio.is_write) ? KVM_TRACE_MMIO_WRITE :
KVM_TRACE_MMIO_READ_UNSATISFIED,
mmio.len, fault_ipa,
- (mmio.is_write) ? *vcpu_reg(vcpu, rt) : 0);
+ (mmio.is_write) ? data : 0);
if (mmio.is_write)
- memcpy(mmio.data, vcpu_reg(vcpu, rt), mmio.len);
+ mmio_write_buf(mmio.data, mmio.len, data);
if (vgic_handle_mmio(vcpu, run, &mmio))
return 1;