[PATCH 17/35] KVM: PPC: Add mtsrin PV code
Alexander Graf
agraf at suse.de
Tue Aug 31 12:31:58 EST 2010
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 at suse.de>
---
Documentation/kvm/ppc-pv.txt | 3 ++
arch/powerpc/kernel/asm-offsets.c | 1 +
arch/powerpc/kernel/kvm.c | 60 +++++++++++++++++++++++++++++++++++++
arch/powerpc/kernel/kvm_emul.S | 50 ++++++++++++++++++++++++++++++
4 files changed, 114 insertions(+), 0 deletions(-)
diff --git a/Documentation/kvm/ppc-pv.txt b/Documentation/kvm/ppc-pv.txt
index 41ee16d..922cf95 100644
--- a/Documentation/kvm/ppc-pv.txt
+++ b/Documentation/kvm/ppc-pv.txt
@@ -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>
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 37486ca..293d2a8 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -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
diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
index f48144f..43ec78a 100644
--- a/arch/powerpc/kernel/kvm.c
+++ b/arch/powerpc/kernel/kvm.c
@@ -43,6 +43,7 @@
#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
@@ -70,6 +71,8 @@
#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;
@@ -265,6 +268,51 @@ 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;
@@ -361,6 +409,18 @@ 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:
diff --git a/arch/powerpc/kernel/kvm_emul.S b/arch/powerpc/kernel/kvm_emul.S
index 3199f65..a6e97e7 100644
--- a/arch/powerpc/kernel/kvm_emul.S
+++ b/arch/powerpc/kernel/kvm_emul.S
@@ -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
--
1.6.0.2
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