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KVM: PPC: Add mtsrin PV code

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This is the guest side of the mtsr acceleration. Using this a guest can now
call mtsrin with almost no overhead as long as it ensures that it only uses
it with (MSR_IR|MSR_DR) == 0. Linux does that, so we're good.

Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Alexander Graf 2010-08-03 10:39:35 +02:00 • committed by Avi Kivity
commit cbe487fac7
4 changed files with 114 additions and 0 deletions
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3
Documentation/kvm/ppc-pv.txt
View file

@ -160,6 +160,9 @@ mtmsr rX b <special mtmsr section>
mtmsrd rX, 1 b <special mtmsrd section>
[Book3S only]
mtsrin rX, rY b <special mtsrin section>
[BookE only]
wrteei [0|1] b <special wrteei section>

1
arch/powerpc/kernel/asm-offsets.c
View file

@ -478,6 +478,7 @@ int main(void)
DEFINE(KVM_MAGIC_MSR, offsetof(struct kvm_vcpu_arch_shared, msr));
DEFINE(KVM_MAGIC_CRITICAL, offsetof(struct kvm_vcpu_arch_shared,
critical));
DEFINE(KVM_MAGIC_SR, offsetof(struct kvm_vcpu_arch_shared, sr));
#endif
#ifdef CONFIG_44x

60
arch/powerpc/kernel/kvm.c
View file

@ -42,6 +42,7 @@
#define KVM_INST_B_MAX 0x01ffffff
#define KVM_MASK_RT 0x03e00000
#define KVM_MASK_RB 0x0000f800
#define KVM_INST_MFMSR 0x7c0000a6
#define KVM_INST_MFSPR_SPRG0 0x7c1042a6
#define KVM_INST_MFSPR_SPRG1 0x7c1142a6
@ -69,6 +70,8 @@
#define KVM_INST_WRTEEI_0 0x7c000146
#define KVM_INST_WRTEEI_1 0x7c008146
#define KVM_INST_MTSRIN 0x7c0001e4
static bool kvm_patching_worked = true;
static char kvm_tmp[1024 * 1024];
static int kvm_tmp_index;
@ -264,6 +267,51 @@ static void kvm_patch_ins_wrteei(u32 *inst)
#endif
#ifdef CONFIG_PPC_BOOK3S_32
extern u32 kvm_emulate_mtsrin_branch_offs;
extern u32 kvm_emulate_mtsrin_reg1_offs;
extern u32 kvm_emulate_mtsrin_reg2_offs;
extern u32 kvm_emulate_mtsrin_orig_ins_offs;
extern u32 kvm_emulate_mtsrin_len;
extern u32 kvm_emulate_mtsrin[];
static void kvm_patch_ins_mtsrin(u32 *inst, u32 rt, u32 rb)
{
u32 *p;
int distance_start;
int distance_end;
ulong next_inst;
p = kvm_alloc(kvm_emulate_mtsrin_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_mtsrin_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_mtsrin, kvm_emulate_mtsrin_len * 4);
p[kvm_emulate_mtsrin_branch_offs] |= distance_end & KVM_INST_B_MASK;
p[kvm_emulate_mtsrin_reg1_offs] |= (rb << 10);
p[kvm_emulate_mtsrin_reg2_offs] |= rt;
p[kvm_emulate_mtsrin_orig_ins_offs] = *inst;
flush_icache_range((ulong)p, (ulong)p + kvm_emulate_mtsrin_len * 4);
/* Patch the invocation */
kvm_patch_ins_b(inst, distance_start);
}
#endif
static void kvm_map_magic_page(void *data)
{
u32 *features = data;
@ -360,6 +408,18 @@ static void kvm_check_ins(u32 *inst, u32 features)
break;
}
switch (inst_no_rt & ~KVM_MASK_RB) {
#ifdef CONFIG_PPC_BOOK3S_32
case KVM_INST_MTSRIN:
if (features & KVM_MAGIC_FEAT_SR) {
u32 inst_rb = _inst & KVM_MASK_RB;
kvm_patch_ins_mtsrin(inst, inst_rt, inst_rb);
}
break;
break;
#endif
}
switch (_inst) {
#ifdef CONFIG_BOOKE
case KVM_INST_WRTEEI_0:

50
arch/powerpc/kernel/kvm_emul.S
View file

@ -245,3 +245,53 @@ kvm_emulate_wrteei_ee_offs:
.global kvm_emulate_wrteei_len
kvm_emulate_wrteei_len:
.long (kvm_emulate_wrteei_end - kvm_emulate_wrteei) / 4
.global kvm_emulate_mtsrin
kvm_emulate_mtsrin:
SCRATCH_SAVE
LL64(r31, KVM_MAGIC_PAGE + KVM_MAGIC_MSR, 0)
andi. r31, r31, MSR_DR | MSR_IR
beq kvm_emulate_mtsrin_reg1
SCRATCH_RESTORE
kvm_emulate_mtsrin_orig_ins:
nop
b kvm_emulate_mtsrin_branch
kvm_emulate_mtsrin_reg1:
/* rX >> 26 */
rlwinm r30,r0,6,26,29
kvm_emulate_mtsrin_reg2:
stw r0, (KVM_MAGIC_PAGE + KVM_MAGIC_SR)(r30)
SCRATCH_RESTORE
/* Go back to caller */
kvm_emulate_mtsrin_branch:
b .
kvm_emulate_mtsrin_end:
.global kvm_emulate_mtsrin_branch_offs
kvm_emulate_mtsrin_branch_offs:
.long (kvm_emulate_mtsrin_branch - kvm_emulate_mtsrin) / 4
.global kvm_emulate_mtsrin_reg1_offs
kvm_emulate_mtsrin_reg1_offs:
.long (kvm_emulate_mtsrin_reg1 - kvm_emulate_mtsrin) / 4
.global kvm_emulate_mtsrin_reg2_offs
kvm_emulate_mtsrin_reg2_offs:
.long (kvm_emulate_mtsrin_reg2 - kvm_emulate_mtsrin) / 4
.global kvm_emulate_mtsrin_orig_ins_offs
kvm_emulate_mtsrin_orig_ins_offs:
.long (kvm_emulate_mtsrin_orig_ins - kvm_emulate_mtsrin) / 4
.global kvm_emulate_mtsrin_len
kvm_emulate_mtsrin_len:
.long (kvm_emulate_mtsrin_end - kvm_emulate_mtsrin) / 4