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authorPaul Mackerras <paulus@samba.org>2013-09-20 08:52:43 +0400
committerAlexander Graf <agraf@suse.de>2013-10-17 16:45:03 +0400
commita2d56020d1d91934e7bb3e7c8a5a3b5921ce121b (patch)
treecebd5519ec61284b8db1ddddfc31236aab6c7628 /arch/powerpc/kvm/book3s_interrupts.S
parentf24817716efe52f3c8fc137c6893963a0416f3cb (diff)
downloadlinux-a2d56020d1d91934e7bb3e7c8a5a3b5921ce121b.tar.xz
KVM: PPC: Book3S PR: Keep volatile reg values in vcpu rather than shadow_vcpu
Currently PR-style KVM keeps the volatile guest register values (R0 - R13, CR, LR, CTR, XER, PC) in a shadow_vcpu struct rather than the main kvm_vcpu struct. For 64-bit, the shadow_vcpu exists in two places, a kmalloc'd struct and in the PACA, and it gets copied back and forth in kvmppc_core_vcpu_load/put(), because the real-mode code can't rely on being able to access the kmalloc'd struct. This changes the code to copy the volatile values into the shadow_vcpu as one of the last things done before entering the guest. Similarly the values are copied back out of the shadow_vcpu to the kvm_vcpu immediately after exiting the guest. We arrange for interrupts to be still disabled at this point so that we can't get preempted on 64-bit and end up copying values from the wrong PACA. This means that the accessor functions in kvm_book3s.h for these registers are greatly simplified, and are same between PR and HV KVM. In places where accesses to shadow_vcpu fields are now replaced by accesses to the kvm_vcpu, we can also remove the svcpu_get/put pairs. Finally, on 64-bit, we don't need the kmalloc'd struct at all any more. With this, the time to read the PVR one million times in a loop went from 567.7ms to 575.5ms (averages of 6 values), an increase of about 1.4% for this worse-case test for guest entries and exits. The standard deviation of the measurements is about 11ms, so the difference is only marginally significant statistically. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'arch/powerpc/kvm/book3s_interrupts.S')
-rw-r--r--arch/powerpc/kvm/book3s_interrupts.S27
1 files changed, 25 insertions, 2 deletions
diff --git a/arch/powerpc/kvm/book3s_interrupts.S b/arch/powerpc/kvm/book3s_interrupts.S
index 17cfae5497a3..d4e30d8fa825 100644
--- a/arch/powerpc/kvm/book3s_interrupts.S
+++ b/arch/powerpc/kvm/book3s_interrupts.S
@@ -26,8 +26,12 @@
#if defined(CONFIG_PPC_BOOK3S_64)
#define FUNC(name) GLUE(.,name)
+#define GET_SHADOW_VCPU(reg) addi reg, r13, PACA_SVCPU
+
#elif defined(CONFIG_PPC_BOOK3S_32)
#define FUNC(name) name
+#define GET_SHADOW_VCPU(reg) lwz reg, (THREAD + THREAD_KVM_SVCPU)(r2)
+
#endif /* CONFIG_PPC_BOOK3S_XX */
#define VCPU_LOAD_NVGPRS(vcpu) \
@@ -87,8 +91,14 @@ kvm_start_entry:
VCPU_LOAD_NVGPRS(r4)
kvm_start_lightweight:
+ /* Copy registers into shadow vcpu so we can access them in real mode */
+ GET_SHADOW_VCPU(r3)
+ bl FUNC(kvmppc_copy_to_svcpu)
+ nop
+ REST_GPR(4, r1)
#ifdef CONFIG_PPC_BOOK3S_64
+ /* Get the dcbz32 flag */
PPC_LL r3, VCPU_HFLAGS(r4)
rldicl r3, r3, 0, 63 /* r3 &= 1 */
stb r3, HSTATE_RESTORE_HID5(r13)
@@ -125,18 +135,31 @@ kvmppc_handler_highmem:
*
*/
- /* R7 = vcpu */
- PPC_LL r7, GPR4(r1)
+ /* Transfer reg values from shadow vcpu back to vcpu struct */
+ /* On 64-bit, interrupts are still off at this point */
+ PPC_LL r3, GPR4(r1) /* vcpu pointer */
+ GET_SHADOW_VCPU(r4)
+ bl FUNC(kvmppc_copy_from_svcpu)
+ nop
#ifdef CONFIG_PPC_BOOK3S_64
+ /* Re-enable interrupts */
+ ld r3, HSTATE_HOST_MSR(r13)
+ ori r3, r3, MSR_EE
+ MTMSR_EERI(r3)
+
/*
* Reload kernel SPRG3 value.
* No need to save guest value as usermode can't modify SPRG3.
*/
ld r3, PACA_SPRG3(r13)
mtspr SPRN_SPRG3, r3
+
#endif /* CONFIG_PPC_BOOK3S_64 */
+ /* R7 = vcpu */
+ PPC_LL r7, GPR4(r1)
+
PPC_STL r14, VCPU_GPR(R14)(r7)
PPC_STL r15, VCPU_GPR(R15)(r7)
PPC_STL r16, VCPU_GPR(R16)(r7)