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.
kvmppc_emulate_instruction() also uses kvmppc_need_byteswap() to
define in which endian order the mmio needs to be done.
The patch is based on Alex Graf's kvm-ppc-queue branch and it
has been tested on Big Endian and Little Endian HV guests and
Big Endian PR guests.
Signed-off-by: Cédric Le Goater <c...@fr.ibm.com>
---
Here are some comments/questions :
* the host is assumed to be running in Big Endian. when Little Endian
hosts are supported in the future, we will use the cpu features to
fix kvmppc_need_byteswap()
* the 'is_bigendian' parameter of the routines kvmppc_handle_load()
and kvmppc_handle_store() seems redundant but the *BRX opcodes
make the improvements unclear. We could eventually rename the
parameter to byteswap and the attribute vcpu->arch.mmio_is_bigendian
to vcpu->arch.mmio_need_byteswap. Anyhow, the current naming sucks
and I would happy to have some directions to fix it.
arch/powerpc/include/asm/kvm_book3s.h | 15 ++++++-
arch/powerpc/kvm/book3s_64_mmu_hv.c | 4 ++
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 14 +++++-
arch/powerpc/kvm/book3s_segment.S | 14 +++++-
arch/powerpc/kvm/emulate.c | 71 +++++++++++++++++--------------
5 files changed, 83 insertions(+), 35 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_book3s.h
b/arch/powerpc/include/asm/kvm_book3s.h
index 0ec00f4..36c5573 100644
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -270,14 +270,22 @@ static inline ulong kvmppc_get_pc(struct kvm_vcpu *vcpu)
return vcpu->arch.pc;
}
+static inline bool kvmppc_need_byteswap(struct kvm_vcpu *vcpu)
+{
+ return vcpu->arch.shared->msr & MSR_LE;
+}
+
static inline u32 kvmppc_get_last_inst(struct kvm_vcpu *vcpu)
{
ulong pc = kvmppc_get_pc(vcpu);
/* Load the instruction manually if it failed to do so in the
* exit path */
- if (vcpu->arch.last_inst == KVM_INST_FETCH_FAILED)
+ if (vcpu->arch.last_inst == KVM_INST_FETCH_FAILED) {
kvmppc_ld(vcpu, &pc, sizeof(u32), &vcpu->arch.last_inst, false);
+ if (kvmppc_need_byteswap(vcpu))
+ vcpu->arch.last_inst = swab32(vcpu->arch.last_inst);
+ }
return vcpu->arch.last_inst;
}
@@ -293,8 +301,11 @@ static inline u32 kvmppc_get_last_sc(struct kvm_vcpu *vcpu)
/* Load the instruction manually if it failed to do so in the
* exit path */
- if (vcpu->arch.last_inst == KVM_INST_FETCH_FAILED)
+ if (vcpu->arch.last_inst == KVM_INST_FETCH_FAILED) {
kvmppc_ld(vcpu, &pc, sizeof(u32), &vcpu->arch.last_inst, false);
+ if (kvmppc_need_byteswap(vcpu))
+ vcpu->arch.last_inst = swab32(vcpu->arch.last_inst);
+ }
return vcpu->arch.last_inst;
}
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c
b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 3a89b85..28130c7 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -547,6 +547,10 @@ static int kvmppc_hv_emulate_mmio(struct kvm_run *run,
struct kvm_vcpu *vcpu,
ret = kvmppc_ld(vcpu, &srr0, sizeof(u32), &last_inst, false);
if (ret != EMULATE_DONE || last_inst == KVM_INST_FETCH_FAILED)
return RESUME_GUEST;
+
+ if (kvmppc_need_byteswap(vcpu))
+ last_inst = swab32(last_inst);
+
vcpu->arch.last_inst = last_inst;
}
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index dd80953..1d3ee40 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1393,14 +1393,26 @@ fast_interrupt_c_return:
lwz r8, 0(r10)
mtmsrd r3
+ ld r0, VCPU_MSR(r9)
+
+ /* r10 = vcpu->arch.msr & MSR_LE */
+ rldicl r10, r0, 0, 63
+ cmpdi r10, 0
+ bne 2f
+
/* Store the result */
stw r8, VCPU_LAST_INST(r9)
/* Unset guest mode. */
- li r0, KVM_GUEST_MODE_NONE
+1: li r0, KVM_GUEST_MODE_NONE
stb r0, HSTATE_IN_GUEST(r13)
b guest_exit_cont
+ /* Swap and store the result */
+2: addi r11, r9, VCPU_LAST_INST
+ stwbrx r8, 0, r11
+ b 1b
+
/*
* Similarly for an HISI, reflect it to the guest as an ISI unless
* it is an HPTE not found fault for a page that we have paged out.
diff --git a/arch/powerpc/kvm/book3s_segment.S
b/arch/powerpc/kvm/book3s_segment.S
index 1abe478..bf20b45 100644
--- a/arch/powerpc/kvm/book3s_segment.S
+++ b/arch/powerpc/kvm/book3s_segment.S
@@ -287,7 +287,19 @@ ld_last_inst:
sync
#endif
- stw r0, SVCPU_LAST_INST(r13)
+ ld r8, SVCPU_SHADOW_SRR1(r13)
+
+ /* r10 = vcpu->arch.msr & MSR_LE */
+ rldicl r10, r0, 0, 63
+ cmpdi r10, 0
+ beq 1f
+
+ /* swap and store the result */
+ addi r11, r13, SVCPU_LAST_INST
+ stwbrx r0, 0, r11
+ b no_ld_last_inst
+
+1: stw r0, SVCPU_LAST_INST(r13)
no_ld_last_inst:
diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index 751cd45..20529ca 100644
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -232,6 +232,7 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct
kvm_vcpu *vcpu)
int sprn = get_sprn(inst);
enum emulation_result emulated = EMULATE_DONE;
int advance = 1;
+ int dont_byteswap = !kvmppc_need_byteswap(vcpu);
/* this default type might be overwritten by subcategories */
kvmppc_set_exit_type(vcpu, EMULATED_INST_EXITS);
@@ -266,47 +267,53 @@ int kvmppc_emulate_instruction(struct kvm_run *run,
struct kvm_vcpu *vcpu)
advance = 0;
break;
case OP_31_XOP_LWZX:
- emulated = kvmppc_handle_load(run, vcpu, rt, 4, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 4,
+ dont_byteswap);
break;
case OP_31_XOP_LBZX:
- emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 1,
+ dont_byteswap);
break;
case OP_31_XOP_LBZUX:
- emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 1,
+ dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
case OP_31_XOP_STWX:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 4, 1);
+ 4, dont_byteswap);
break;
case OP_31_XOP_STBX:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 1, 1);
+ 1, dont_byteswap);
break;
case OP_31_XOP_STBUX:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 1, 1);
+ 1, dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
case OP_31_XOP_LHAX:
- emulated = kvmppc_handle_loads(run, vcpu, rt, 2, 1);
+ emulated = kvmppc_handle_loads(run, vcpu, rt, 2,
+ dont_byteswap);
break;
case OP_31_XOP_LHZX:
- emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 2,
+ dont_byteswap);
break;
case OP_31_XOP_LHZUX:
- emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 2,
+ dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
@@ -317,13 +324,13 @@ int kvmppc_emulate_instruction(struct kvm_run *run,
struct kvm_vcpu *vcpu)
case OP_31_XOP_STHX:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 2, 1);
+ 2, dont_byteswap);
break;
case OP_31_XOP_STHUX:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 2, 1);
+ 2, dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
@@ -342,7 +349,8 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct
kvm_vcpu *vcpu)
break;
case OP_31_XOP_LWBRX:
- emulated = kvmppc_handle_load(run, vcpu, rt, 4, 0);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 4,
+ !dont_byteswap);
break;
case OP_31_XOP_TLBSYNC:
@@ -351,17 +359,18 @@ int kvmppc_emulate_instruction(struct kvm_run *run,
struct kvm_vcpu *vcpu)
case OP_31_XOP_STWBRX:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 4, 0);
+ 4, !dont_byteswap);
break;
case OP_31_XOP_LHBRX:
- emulated = kvmppc_handle_load(run, vcpu, rt, 2, 0);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 2,
+ !dont_byteswap);
break;
case OP_31_XOP_STHBRX:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 2, 0);
+ 2, !dont_byteswap);
break;
default:
@@ -371,33 +380,33 @@ int kvmppc_emulate_instruction(struct kvm_run *run,
struct kvm_vcpu *vcpu)
break;
case OP_LWZ:
- emulated = kvmppc_handle_load(run, vcpu, rt, 4, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 4, dont_byteswap);
break;
/* TBD: Add support for other 64 bit load variants like ldu, ldux, ldx
etc. */
case OP_LD:
rt = get_rt(inst);
- emulated = kvmppc_handle_load(run, vcpu, rt, 8, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 8, dont_byteswap);
break;
case OP_LWZU:
- emulated = kvmppc_handle_load(run, vcpu, rt, 4, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 4, dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
case OP_LBZ:
- emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 1, dont_byteswap);
break;
case OP_LBZU:
- emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 1, dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
case OP_STW:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 4, 1);
+ 4, dont_byteswap);
break;
/* TBD: Add support for other 64 bit store variants like stdu, stdux,
stdx etc. */
@@ -405,57 +414,57 @@ int kvmppc_emulate_instruction(struct kvm_run *run,
struct kvm_vcpu *vcpu)
rs = get_rs(inst);
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 8, 1);
+ 8, dont_byteswap);
break;
case OP_STWU:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 4, 1);
+ 4, dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
case OP_STB:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 1, 1);
+ 1, dont_byteswap);
break;
case OP_STBU:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 1, 1);
+ 1, dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
case OP_LHZ:
- emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 2, dont_byteswap);
break;
case OP_LHZU:
- emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
+ emulated = kvmppc_handle_load(run, vcpu, rt, 2, dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
case OP_LHA:
- emulated = kvmppc_handle_loads(run, vcpu, rt, 2, 1);
+ emulated = kvmppc_handle_loads(run, vcpu, rt, 2, dont_byteswap);
break;
case OP_LHAU:
- emulated = kvmppc_handle_loads(run, vcpu, rt, 2, 1);
+ emulated = kvmppc_handle_loads(run, vcpu, rt, 2, dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
case OP_STH:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 2, 1);
+ 2, dont_byteswap);
break;
case OP_STHU:
emulated = kvmppc_handle_store(run, vcpu,
kvmppc_get_gpr(vcpu, rs),
- 2, 1);
+ 2, dont_byteswap);
kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
break;
--
1.7.10.4
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