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>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 5a285efba174..fda7f4020a33 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -520,6 +520,7 @@ int main(void)
         DEFINE(VCPU_PTID, offsetof(struct kvm_vcpu, arch.ptid));
         DEFINE(VCPU_CFAR, offsetof(struct kvm_vcpu, arch.cfar));
         DEFINE(VCPU_PPR, offsetof(struct kvm_vcpu, arch.ppr));
+        DEFINE(VCPU_SHADOW_SRR1, offsetof(struct kvm_vcpu, arch.shadow_srr1));
         DEFINE(VCORE_ENTRY_EXIT, offsetof(struct kvmppc_vcore, entry_exit_count));
         DEFINE(VCORE_NAP_COUNT, offsetof(struct kvmppc_vcore, nap_count));
         DEFINE(VCORE_IN_GUEST, offsetof(struct kvmppc_vcore, in_guest));
@@ -527,14 +528,13 @@ int main(void)
         DEFINE(VCORE_TB_OFFSET, offsetof(struct kvmppc_vcore, tb_offset));
         DEFINE(VCORE_LPCR, offsetof(struct kvmppc_vcore, lpcr));
         DEFINE(VCORE_PCR, offsetof(struct kvmppc_vcore, pcr));
-        DEFINE(VCPU_SVCPU, offsetof(struct kvmppc_vcpu_book3s, shadow_vcpu) -
-                           offsetof(struct kvmppc_vcpu_book3s, vcpu));
         DEFINE(VCPU_SLB_E, offsetof(struct kvmppc_slb, orige));
         DEFINE(VCPU_SLB_V, offsetof(struct kvmppc_slb, origv));
         DEFINE(VCPU_SLB_SIZE, sizeof(struct kvmppc_slb));
 
 #ifdef CONFIG_PPC_BOOK3S_64
 #ifdef CONFIG_KVM_BOOK3S_PR
+        DEFINE(PACA_SVCPU, offsetof(struct paca_struct, shadow_vcpu));
 # define SVCPU_FIELD(x, f)      DEFINE(x, offsetof(struct paca_struct, shadow_vcpu.f))
 #else
 # define SVCPU_FIELD(x, f)