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authorAlexander Graf <agraf@suse.de>2010-07-29 14:48:03 +0200
committerAvi Kivity <avi@redhat.com>2010-10-24 10:50:55 +0200
commit92234722ed631f472f1c4d79d35d8e5cf6910002 (patch)
tree482fac5bdebbe2b19cda8a2575e3805d99f23310 /arch/powerpc
parent71ee8e34fe26252b11668a95708783ec9c58cbda (diff)
KVM: PPC: PV assembler helpers
When we hook an instruction we need to make sure we don't clobber any of the registers at that point. So we write them out to scratch space in the magic page. To make sure we don't fall into a race with another piece of hooked code, we need to disable interrupts. To make the later patches and code in general easier readable, let's introduce a set of defines that save and restore r30, r31 and cr. Let's also define some helpers to read the lower 32 bits of a 64 bit field on 32 bit systems. Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kernel/kvm_emul.S30
1 files changed, 30 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/kvm_emul.S b/arch/powerpc/kernel/kvm_emul.S
index 5cfa2aeeecb..1dac72dd6f6 100644
--- a/arch/powerpc/kernel/kvm_emul.S
+++ b/arch/powerpc/kernel/kvm_emul.S
@@ -34,3 +34,33 @@ kvm_hypercall_start:
blr
#define KVM_MAGIC_PAGE (-4096)
+
+#ifdef CONFIG_64BIT
+#define LL64(reg, offs, reg2) ld reg, (offs)(reg2)
+#define STL64(reg, offs, reg2) std reg, (offs)(reg2)
+#else
+#define LL64(reg, offs, reg2) lwz reg, (offs + 4)(reg2)
+#define STL64(reg, offs, reg2) stw reg, (offs + 4)(reg2)
+#endif
+
+#define SCRATCH_SAVE \
+ /* Enable critical section. We are critical if \
+ shared->critical == r1 */ \
+ STL64(r1, KVM_MAGIC_PAGE + KVM_MAGIC_CRITICAL, 0); \
+ \
+ /* Save state */ \
+ PPC_STL r31, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH1)(0); \
+ PPC_STL r30, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH2)(0); \
+ mfcr r31; \
+ stw r31, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH3)(0);
+
+#define SCRATCH_RESTORE \
+ /* Restore state */ \
+ PPC_LL r31, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH1)(0); \
+ lwz r30, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH3)(0); \
+ mtcr r30; \
+ PPC_LL r30, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH2)(0); \
+ \
+ /* Disable critical section. We are critical if \
+ shared->critical == r1 and r2 is always != r1 */ \
+ STL64(r2, KVM_MAGIC_PAGE + KVM_MAGIC_CRITICAL, 0);