KVM: s390: rewrite vcpu_post_run and drop out early

Let's rewrite this function to better reflect how we actually handle
exit_code. By dropping out early we can save a few cycles. This
especially speeds up sie exits caused by host irqs.

Also, let's move the special -EOPNOTSUPP for intercepts to
the place where it belongs and convert it to -EREMOTE.

Reviewed-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index b4a5aa110cec0b7ea62a534769812a2782b8cc35..d53c10753c466b47b6fcb4813ec9e3445ca47a04 100644 (file)
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -54,9 +54,6 @@ void kvm_s390_rewind_psw(struct kvm_vcpu *vcpu, int ilc)
 static int handle_noop(struct kvm_vcpu *vcpu)
 {
        switch (vcpu->arch.sie_block->icptcode) {
-       case 0x0:
-               vcpu->stat.exit_null++;
-               break;
        case 0x10:
                vcpu->stat.exit_external_request++;
                break;
@@ -338,8 +335,10 @@ static int handle_partial_execution(struct kvm_vcpu *vcpu)
 
 int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
 {
+       if (kvm_is_ucontrol(vcpu->kvm))
+               return -EOPNOTSUPP;
+
        switch (vcpu->arch.sie_block->icptcode) {
-       case 0x00:
        case 0x10:
        case 0x18:
                return handle_noop(vcpu);

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 846589281b046f414837cbd3f7ab9f4d0c675a51..5c36c8e7e937a73ec7349b63435fb0cf1966644e 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2071,8 +2071,6 @@ static int vcpu_post_run_fault_in_sie(struct kvm_vcpu *vcpu)
 
 static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason)
 {
-       int rc = -1;
-
        VCPU_EVENT(vcpu, 6, "exit sie icptcode %d",
                   vcpu->arch.sie_block->icptcode);
        trace_kvm_s390_sie_exit(vcpu, vcpu->arch.sie_block->icptcode);
@@ -2080,40 +2078,35 @@ static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason)
        if (guestdbg_enabled(vcpu))
                kvm_s390_restore_guest_per_regs(vcpu);
 
-       if (exit_reason >= 0) {
-               rc = 0;
+       memcpy(&vcpu->run->s.regs.gprs[14], &vcpu->arch.sie_block->gg14, 16);
+
+       if (vcpu->arch.sie_block->icptcode > 0) {
+               int rc = kvm_handle_sie_intercept(vcpu);
+
+               if (rc != -EOPNOTSUPP)
+                       return rc;
+               vcpu->run->exit_reason = KVM_EXIT_S390_SIEIC;
+               vcpu->run->s390_sieic.icptcode = vcpu->arch.sie_block->icptcode;
+               vcpu->run->s390_sieic.ipa = vcpu->arch.sie_block->ipa;
+               vcpu->run->s390_sieic.ipb = vcpu->arch.sie_block->ipb;
+               return -EREMOTE;
+       } else if (exit_reason != -EFAULT) {
+               vcpu->stat.exit_null++;
+               return 0;
        } else if (kvm_is_ucontrol(vcpu->kvm)) {
                vcpu->run->exit_reason = KVM_EXIT_S390_UCONTROL;
                vcpu->run->s390_ucontrol.trans_exc_code =
                                                current->thread.gmap_addr;
                vcpu->run->s390_ucontrol.pgm_code = 0x10;
-               rc = -EREMOTE;
-
+               return -EREMOTE;
        } else if (current->thread.gmap_pfault) {
                trace_kvm_s390_major_guest_pfault(vcpu);
                current->thread.gmap_pfault = 0;
-               if (kvm_arch_setup_async_pf(vcpu)) {
-                       rc = 0;
-               } else {
-                       gpa_t gpa = current->thread.gmap_addr;
-                       rc = kvm_arch_fault_in_page(vcpu, gpa, 1);
-               }
-       }
-
-       if (rc == -1)
-               rc = vcpu_post_run_fault_in_sie(vcpu);
-
-       memcpy(&vcpu->run->s.regs.gprs[14], &vcpu->arch.sie_block->gg14, 16);
-
-       if (rc == 0) {
-               if (kvm_is_ucontrol(vcpu->kvm))
-                       /* Don't exit for host interrupts. */
-                       rc = vcpu->arch.sie_block->icptcode ? -EOPNOTSUPP : 0;
-               else
-                       rc = kvm_handle_sie_intercept(vcpu);
+               if (kvm_arch_setup_async_pf(vcpu))
+                       return 0;
+               return kvm_arch_fault_in_page(vcpu, current->thread.gmap_addr, 1);
        }
-
-       return rc;
+       return vcpu_post_run_fault_in_sie(vcpu);
 }
 
 static int __vcpu_run(struct kvm_vcpu *vcpu)
@@ -2233,18 +2226,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
                rc = 0;
        }
 
-       if (rc == -EOPNOTSUPP) {
-               /* intercept cannot be handled in-kernel, prepare kvm-run */
-               kvm_run->exit_reason         = KVM_EXIT_S390_SIEIC;
-               kvm_run->s390_sieic.icptcode = vcpu->arch.sie_block->icptcode;
-               kvm_run->s390_sieic.ipa      = vcpu->arch.sie_block->ipa;
-               kvm_run->s390_sieic.ipb      = vcpu->arch.sie_block->ipb;
-               rc = 0;
-       }
-
        if (rc == -EREMOTE) {
-               /* intercept was handled, but userspace support is needed
-                * kvm_run has been prepared by the handler */
+               /* userspace support is needed, kvm_run has been prepared */
                rc = 0;
        }