MMIO emulation reads the last instruction executed by the guest
and then emulates. If the guest is running in Little Endian mode,
the instruction needs to be byte-swapped before being emulated.
This patch stores the last instruction in the endian order of the
host, primarily doing a byte-swap if needed. The common code
which fetches 'last_inst' uses a helper routine kvmppc_need_byteswap().
and the exit paths for the Book3S PV and HR guests use their own
version in assembly.
Finally, the meaning of the 'is_bigendian' argument of the
routines kvmppc_handle_load() of kvmppc_handle_store() is
slightly changed to represent an eventual reverse operation. This
is used in conjunction with kvmppc_is_bigendian() to determine if
the instruction being emulated should be byte-swapped.
Signed-off-by: Cédric Le Goater <clg@xxxxxxxxxx>
---
Changes in v3:
- moved kvmppc_need_byteswap() in kvmppc_ld32. It previously was in
kvmppc_ld_inst(). (Alexander Graf)
Changes in v2:
- replaced rldicl. by andi. to test the MSR_LE bit in the guest
exit paths. (Paul Mackerras)
- moved the byte swapping logic to kvmppc_handle_load() and
kvmppc_handle_load() by changing the is_bigendian parameter
meaning. (Paul Mackerras)
arch/powerpc/include/asm/kvm_book3s.h | 9 ++++++++-
arch/powerpc/include/asm/kvm_ppc.h | 10 +++++-----
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 +++++++++++
arch/powerpc/kvm/book3s_segment.S | 10 ++++++++++
arch/powerpc/kvm/emulate.c | 1 -
arch/powerpc/kvm/powerpc.c | 16 ++++++++++++----
6 files changed, 46 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
index 4ee6c66..9403042 100644
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -283,7 +283,14 @@ static inline bool kvmppc_is_bigendian(struct kvm_vcpu *vcpu)
static inline int kvmppc_ld32(struct kvm_vcpu *vcpu, ulong *eaddr,
u32 *ptr, bool data)
{
- return kvmppc_ld(vcpu, eaddr, sizeof(u32), ptr, data);
+ int ret;
+
+ ret = kvmppc_ld(vcpu, eaddr, sizeof(u32), ptr, data);
+
+ if (kvmppc_need_byteswap(vcpu))
+ *ptr = swab32(*ptr);
+
+ return ret;
}
static inline int kvmppc_ld_inst(struct kvm_vcpu *vcpu, ulong *eaddr,
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index b15554a..3769a13 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -53,13 +53,13 @@ extern void kvmppc_handler_highmem(void);
extern void kvmppc_dump_vcpu(struct kvm_vcpu *vcpu);
extern int kvmppc_handle_load(struct kvm_run *run, struct kvm_vcpu *vcpu,
- unsigned int rt, unsigned int bytes,
- int is_bigendian);
+ unsigned int rt, unsigned int bytes,
+ int not_reverse);
extern int kvmppc_handle_loads(struct kvm_run *run, struct kvm_vcpu *vcpu,
- unsigned int rt, unsigned int bytes,
- int is_bigendian);
+ unsigned int rt, unsigned int bytes,
+ int not_reverse);
extern int kvmppc_handle_store(struct kvm_run *run, struct kvm_vcpu *vcpu,
- u64 val, unsigned int bytes, int is_bigendian);
+ u64 val, unsigned int bytes, int not_reverse);
extern int kvmppc_emulate_instruction(struct kvm_run *run,
struct kvm_vcpu *vcpu);
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 77f1baa..ff7da8b 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1404,10 +1404,21 @@ fast_interrupt_c_return:
lwz r8, 0(r10)
mtmsrd r3
+ ld r0, VCPU_MSR(r9)
+
+ andi. r10, r0, MSR_LE
+
/* Store the result */
stw r8, VCPU_LAST_INST(r9)
+ beq after_inst_store
+
+ /* Swap and store the result */
+ addi r11, r9, VCPU_LAST_INST
+ stwbrx r8, 0, r11
+
/* Unset guest mode. */
+after_inst_store:
li r0, KVM_GUEST_MODE_HOST_HV
stb r0, HSTATE_IN_GUEST(r13)
b guest_exit_cont
diff --git a/arch/powerpc/kvm/book3s_segment.S b/arch/powerpc/kvm/book3s_segment.S
index 1abe478..677ef7a 100644
--- a/arch/powerpc/kvm/book3s_segment.S
+++ b/arch/powerpc/kvm/book3s_segment.S
@@ -287,8 +287,18 @@ ld_last_inst:
sync
#endif
+ ld r8, SVCPU_SHADOW_SRR1(r13)
+
+ andi. r10, r8, MSR_LE
+
stw r0, SVCPU_LAST_INST(r13)
+ beq no_ld_last_inst
+
+ /* swap and store the result */
+ addi r11, r13, SVCPU_LAST_INST
+ stwbrx r0, 0, r11
+
no_ld_last_inst:
/* Unset guest mode */
diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index 751cd45..5e38004 100644
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -219,7 +219,6 @@ static int kvmppc_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt)
* lmw
* stmw
*
- * XXX is_bigendian should depend on MMU mapping or MSR[LE]
*/
/* XXX Should probably auto-generate instruction decoding for a particular core
* from opcode tables in the future. */
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 07c0106..6950f2b 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -625,9 +625,13 @@ static void kvmppc_complete_mmio_load(struct kvm_vcpu *vcpu,
}
int kvmppc_handle_load(struct kvm_run *run, struct kvm_vcpu *vcpu,
- unsigned int rt, unsigned int bytes, int is_bigendian)
+ unsigned int rt, unsigned int bytes, int not_reverse)
{
int idx, ret;
+ int is_bigendian = not_reverse;
+
+ if (!kvmppc_is_bigendian(vcpu))
+ is_bigendian = !not_reverse;
if (bytes > sizeof(run->mmio.data)) {
printk(KERN_ERR "%s: bad MMIO length: %d\n", __func__,
@@ -662,21 +666,25 @@ int kvmppc_handle_load(struct kvm_run *run, struct kvm_vcpu *vcpu,
/* Same as above, but sign extends */
int kvmppc_handle_loads(struct kvm_run *run, struct kvm_vcpu *vcpu,
- unsigned int rt, unsigned int bytes, int is_bigendian)
+ unsigned int rt, unsigned int bytes, int not_reverse)
{
int r;
vcpu->arch.mmio_sign_extend = 1;
- r = kvmppc_handle_load(run, vcpu, rt, bytes, is_bigendian);
+ r = kvmppc_handle_load(run, vcpu, rt, bytes, not_reverse);
return r;
}
int kvmppc_handle_store(struct kvm_run *run, struct kvm_vcpu *vcpu,
- u64 val, unsigned int bytes, int is_bigendian)
+ u64 val, unsigned int bytes, int not_reverse)
{
void *data = run->mmio.data;
int idx, ret;
+ int is_bigendian = not_reverse;
+
+ if (!kvmppc_is_bigendian(vcpu))
+ is_bigendian = !not_reverse;
if (bytes > sizeof(run->mmio.data)) {
printk(KERN_ERR "%s: bad MMIO length: %d\n", __func__,
--
1.7.10.4
--
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