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KVM: PPC: PV mtmsrd L=0 and mtmsr 

There is also a form of mtmsr where all bits need to be addressed. While the
PPC64 Linux kernel behaves resonably well here, on PPC32 we do not have an
L=1 form. It does mtmsr even for simple things like only changing EE.

So we need to hook into that one as well and check for a mask of bits that we
deem safe to change from within guest context.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
hifive-unleashed-5.1
Alexander Graf 2010-07-29 14:48:05 +02:00 committed by Avi Kivity
parent 819a63dc79
commit 7810927760
2 changed files with 135 additions and 0 deletions
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51
arch/powerpc/kernel/kvm.c
View File

@ -63,7 +63,9 @@
#define KVM_INST_MTSPR_DSISR 0x7c1203a6
#define KVM_INST_TLBSYNC 0x7c00046c
#define KVM_INST_MTMSRD_L0 0x7c000164
#define KVM_INST_MTMSRD_L1 0x7c010164
#define KVM_INST_MTMSR 0x7c000124
static bool kvm_patching_worked = true;
static char kvm_tmp[1024 * 1024];
@ -176,6 +178,49 @@ static void kvm_patch_ins_mtmsrd(u32 *inst, u32 rt)
kvm_patch_ins_b(inst, distance_start);
}
extern u32 kvm_emulate_mtmsr_branch_offs;
extern u32 kvm_emulate_mtmsr_reg1_offs;
extern u32 kvm_emulate_mtmsr_reg2_offs;
extern u32 kvm_emulate_mtmsr_reg3_offs;
extern u32 kvm_emulate_mtmsr_orig_ins_offs;
extern u32 kvm_emulate_mtmsr_len;
extern u32 kvm_emulate_mtmsr[];
static void kvm_patch_ins_mtmsr(u32 *inst, u32 rt)
{
u32 *p;
int distance_start;
int distance_end;
ulong next_inst;
p = kvm_alloc(kvm_emulate_mtmsr_len * 4);
if (!p)
return;
/* Find out where we are and put everything there */
distance_start = (ulong)p - (ulong)inst;
next_inst = ((ulong)inst + 4);
distance_end = next_inst - (ulong)&p[kvm_emulate_mtmsr_branch_offs];
/* Make sure we only write valid b instructions */
if (distance_start > KVM_INST_B_MAX) {
kvm_patching_worked = false;
return;
}
/* Modify the chunk to fit the invocation */
memcpy(p, kvm_emulate_mtmsr, kvm_emulate_mtmsr_len * 4);
p[kvm_emulate_mtmsr_branch_offs] |= distance_end & KVM_INST_B_MASK;
p[kvm_emulate_mtmsr_reg1_offs] |= rt;
p[kvm_emulate_mtmsr_reg2_offs] |= rt;
p[kvm_emulate_mtmsr_reg3_offs] |= rt;
p[kvm_emulate_mtmsr_orig_ins_offs] = *inst;
flush_icache_range((ulong)p, (ulong)p + kvm_emulate_mtmsr_len * 4);
/* Patch the invocation */
kvm_patch_ins_b(inst, distance_start);
}
static void kvm_map_magic_page(void *data)
{
kvm_hypercall2(KVM_HC_PPC_MAP_MAGIC_PAGE,
@ -256,6 +301,12 @@ static void kvm_check_ins(u32 *inst)
if (get_rt(inst_rt) < 30)
kvm_patch_ins_mtmsrd(inst, inst_rt);
break;
case KVM_INST_MTMSR:
case KVM_INST_MTMSRD_L0:
/* We use r30 and r31 during the hook */
if (get_rt(inst_rt) < 30)
kvm_patch_ins_mtmsr(inst, inst_rt);
break;
}
switch (_inst) {

84
arch/powerpc/kernel/kvm_emul.S
View File

@ -120,3 +120,87 @@ kvm_emulate_mtmsrd_reg_offs:
.global kvm_emulate_mtmsrd_len
kvm_emulate_mtmsrd_len:
.long (kvm_emulate_mtmsrd_end - kvm_emulate_mtmsrd) / 4
#define MSR_SAFE_BITS (MSR_EE | MSR_CE | MSR_ME | MSR_RI)
#define MSR_CRITICAL_BITS ~MSR_SAFE_BITS
.global kvm_emulate_mtmsr
kvm_emulate_mtmsr:
SCRATCH_SAVE
/* Fetch old MSR in r31 */
LL64(r31, KVM_MAGIC_PAGE + KVM_MAGIC_MSR, 0)
/* Find the changed bits between old and new MSR */
kvm_emulate_mtmsr_reg1:
xor r31, r0, r31
/* Check if we need to really do mtmsr */
LOAD_REG_IMMEDIATE(r30, MSR_CRITICAL_BITS)
and. r31, r31, r30
/* No critical bits changed? Maybe we can stay in the guest. */
beq maybe_stay_in_guest
do_mtmsr:
SCRATCH_RESTORE
/* Just fire off the mtmsr if it's critical */
kvm_emulate_mtmsr_orig_ins:
mtmsr r0
b kvm_emulate_mtmsr_branch
maybe_stay_in_guest:
/* Check if we have to fetch an interrupt */
lwz r31, (KVM_MAGIC_PAGE + KVM_MAGIC_INT)(0)
cmpwi r31, 0
beq+ no_mtmsr
/* Check if we may trigger an interrupt */
kvm_emulate_mtmsr_reg2:
andi. r31, r0, MSR_EE
beq no_mtmsr
b do_mtmsr
no_mtmsr:
/* Put MSR into magic page because we don't call mtmsr */
kvm_emulate_mtmsr_reg3:
STL64(r0, KVM_MAGIC_PAGE + KVM_MAGIC_MSR, 0)
SCRATCH_RESTORE
/* Go back to caller */
kvm_emulate_mtmsr_branch:
b .
kvm_emulate_mtmsr_end:
.global kvm_emulate_mtmsr_branch_offs
kvm_emulate_mtmsr_branch_offs:
.long (kvm_emulate_mtmsr_branch - kvm_emulate_mtmsr) / 4
.global kvm_emulate_mtmsr_reg1_offs
kvm_emulate_mtmsr_reg1_offs:
.long (kvm_emulate_mtmsr_reg1 - kvm_emulate_mtmsr) / 4
.global kvm_emulate_mtmsr_reg2_offs
kvm_emulate_mtmsr_reg2_offs:
.long (kvm_emulate_mtmsr_reg2 - kvm_emulate_mtmsr) / 4
.global kvm_emulate_mtmsr_reg3_offs
kvm_emulate_mtmsr_reg3_offs:
.long (kvm_emulate_mtmsr_reg3 - kvm_emulate_mtmsr) / 4
.global kvm_emulate_mtmsr_orig_ins_offs
kvm_emulate_mtmsr_orig_ins_offs:
.long (kvm_emulate_mtmsr_orig_ins - kvm_emulate_mtmsr) / 4
.global kvm_emulate_mtmsr_len
kvm_emulate_mtmsr_len:
.long (kvm_emulate_mtmsr_end - kvm_emulate_mtmsr) / 4