KVM: s390: Use generic VIRT_XFER_TO_GUEST_WORK functions

Switch to using the generic infrastructure to check for and handle pending
work before transitioning into guest mode.

xfer_to_guest_mode_handle_work() does a few more things than the current
code does when deciding whether or not to exit the __vcpu_run() loop. The
exittime tests from kvm-unit-tests, in my tests, were within a few percent
compared to before this series, which is within noise tolerance.

Co-developed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
[frankja@linux.ibm.com: Removed semicolon]
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>

1 files changed, 18 insertions, 7 deletions

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 4d13601ec217..d31155e371df 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -14,6 +14,7 @@
 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
 
 #include <linux/compiler.h>
+#include <linux/entry-virt.h>
 #include <linux/export.h>
 #include <linux/err.h>
 #include <linux/fs.h>
@@ -4675,9 +4676,6 @@ static int vcpu_pre_run(struct kvm_vcpu *vcpu)
 	vcpu->arch.sie_block->gg14 = vcpu->run->s.regs.gprs[14];
 	vcpu->arch.sie_block->gg15 = vcpu->run->s.regs.gprs[15];
 
-	if (need_resched())
-		schedule();
-
 	if (!kvm_is_ucontrol(vcpu->kvm)) {
 		rc = kvm_s390_deliver_pending_interrupts(vcpu);
 		if (rc || guestdbg_exit_pending(vcpu))
@@ -4982,12 +4980,12 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
 	 */
 	kvm_vcpu_srcu_read_lock(vcpu);
 
-	do {
+	while (true) {
 		rc = vcpu_pre_run(vcpu);
+		kvm_vcpu_srcu_read_unlock(vcpu);
 		if (rc || guestdbg_exit_pending(vcpu))
 			break;
 
-		kvm_vcpu_srcu_read_unlock(vcpu);
 		/*
 		 * As PF_VCPU will be used in fault handler, between
 		 * guest_timing_enter_irqoff and guest_timing_exit_irqoff
@@ -4999,7 +4997,17 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
 			       sizeof(sie_page->pv_grregs));
 		}
 
+xfer_to_guest_mode_check:
 		local_irq_disable();
+		xfer_to_guest_mode_prepare();
+		if (xfer_to_guest_mode_work_pending()) {
+			local_irq_enable();
+			rc = kvm_xfer_to_guest_mode_handle_work(vcpu);
+			if (rc)
+				break;
+			goto xfer_to_guest_mode_check;
+		}
+
 		guest_timing_enter_irqoff();
 		__disable_cpu_timer_accounting(vcpu);
 
@@ -5029,9 +5037,12 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
 		kvm_vcpu_srcu_read_lock(vcpu);
 
 		rc = vcpu_post_run(vcpu, exit_reason);
-	} while (!signal_pending(current) && !guestdbg_exit_pending(vcpu) && !rc);
+		if (rc || guestdbg_exit_pending(vcpu)) {
+			kvm_vcpu_srcu_read_unlock(vcpu);
+			break;
+		}
+	}
 
-	kvm_vcpu_srcu_read_unlock(vcpu);
 	return rc;
 }