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powerpc: kvm: optimize "sc 1" as fast return 

In some scene, e.g openstack CI, PR guest can trigger "sc 1" frequently,
this patch optimizes the path by directly delivering BOOK3S_INTERRUPT_SYSCALL
to HV guest, so powernv can return to HV guest without heavy exit, i.e,
no need to swap TLB, HTAB,.. etc

Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Liu Ping Fan 2013-11-19 14:12:48 +08:00 committed by Alexander Graf
parent 8a3caa6d74
commit 27025a602c
2 changed files with 22 additions and 7 deletions
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10
arch/powerpc/kvm/book3s_hv.c
View File

@ -669,12 +669,10 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu,
/* hcall - punt to userspace */
int i;
if (vcpu->arch.shregs.msr & MSR_PR) {
/* sc 1 from userspace - reflect to guest syscall */
kvmppc_book3s_queue_irqprio(vcpu, BOOK3S_INTERRUPT_SYSCALL);
r = RESUME_GUEST;
break;
}
/* hypercall with MSR_PR has already been handled in rmode,
* and never reaches here.
*/
run->papr_hcall.nr = kvmppc_get_gpr(vcpu, 3);
for (i = 0; i < 9; ++i)
run->papr_hcall.args[i] = kvmppc_get_gpr(vcpu, 4 + i);

19
arch/powerpc/kvm/book3s_hv_rmhandlers.S
View File

@ -686,6 +686,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_206)
5: mtspr SPRN_SRR0, r6
mtspr SPRN_SRR1, r7
/*
* Required state:
* R4 = vcpu
* R10: value for HSRR0
* R11: value for HSRR1
* R13 = PACA
*/
fast_guest_return:
li r0,0
stb r0,VCPU_CEDED(r4) /* cancel cede */
@ -1471,7 +1478,8 @@ kvmppc_hisi:
hcall_try_real_mode:
ld r3,VCPU_GPR(R3)(r9)
andi. r0,r11,MSR_PR
bne guest_exit_cont
/* sc 1 from userspace - reflect to guest syscall */
bne sc_1_fast_return
clrrdi r3,r3,2
cmpldi r3,hcall_real_table_end - hcall_real_table
bge guest_exit_cont
@ -1492,6 +1500,15 @@ hcall_try_real_mode:
ld r11,VCPU_MSR(r4)
b fast_guest_return
sc_1_fast_return:
mtspr SPRN_SRR0,r10
mtspr SPRN_SRR1,r11
li r10, BOOK3S_INTERRUPT_SYSCALL
li r11, (MSR_ME << 1) | 1 /* synthesize MSR_SF | MSR_ME */
rotldi r11, r11, 63
mr r4,r9
b fast_guest_return
/* We've attempted a real mode hcall, but it's punted it back
* to userspace. We need to restore some clobbered volatiles
* before resuming the pass-it-to-qemu path */