From a2d56020d1d91934e7bb3e7c8a5a3b5921ce121b Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Fri, 20 Sep 2013 14:52:43 +1000 Subject: 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 Signed-off-by: Alexander Graf --- arch/powerpc/kvm/book3s_interrupts.S | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) (limited to 'arch/powerpc/kvm/book3s_interrupts.S') 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) -- cgit v1.2.1