syscall is a very common behavior inside guest, and this patch
optimizes the path for the emulation of BOOK3S_INTERRUPT_SYSCALL,
so hypervisor can return to guest without heavy exit, i.e, no need
to swap TLB, HTAB,.. etc
Signed-off-by: Liu Ping Fan <pingfank@xxxxxxxxxxxxxxxxxx>
---
Compiled, but lack of bare metal, I have not tested it yet.
---
arch/powerpc/kvm/book3s_hv.c | 6 ------
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 13 ++++++++++++-
2 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 62a2b5a..73dc852 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -628,12 +628,6 @@ static int kvmppc_handle_exit(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;
- }
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);
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index c71103b..9f626c3 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1388,7 +1388,8 @@ 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_0_fast_return
clrrdi r3,r3,2
cmpldi r3,hcall_real_table_end - hcall_real_table
bge guest_exit_cont
@@ -1409,6 +1410,16 @@ hcall_try_real_mode:
ld r11,VCPU_MSR(r4)
b fast_guest_return
+sc_0_fast_return:
+ ld r10,VCPU_PC(r9)
+ ld r11,VCPU_MSR(r9)
+ mtspr SPRN_SRR0,r10
+ mtspr SPRN_SRR1,r11
+ li r10, BOOK3S_INTERRUPT_SYSCALL
+ LOAD_REG_IMMEDIATE(r3,0xffffffff87a0ffff) /* zero 33:36,42:47 */
+ and r11,r11,r3
+ 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 */
--
1.8.1.4
--
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