Commit 2bd1337a authored by Andrew Donnellan's avatar Andrew Donnellan Committed by Janosch Frank
Browse files

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: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Acked-by: default avatarJanosch Frank <frankja@linux.ibm.com>
[frankja@linux.ibm.com: Removed semicolon]
Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
parent d0139059

arch/s390/kvm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ config KVM 
	select HAVE_KVM_NO_POLL

	select KVM_VFIO

	select MMU_NOTIFIER

	select VIRT_XFER_TO_GUEST_WORK

	help

	  Support hosting paravirtualized guest machines using the SIE

	  virtualization capability on the mainframe. This should work

arch/s390/kvm/kvm-s390.c

+18 −7
Original line number Diff line number Diff line
@@ -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;

		}

	}



	return rc;

}

arch/s390/kvm/vsie.c

+13 −5
Original line number Diff line number Diff line
@@ -1180,12 +1180,23 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) 
	current->thread.gmap_int_code = 0;

	barrier();

	if (!kvm_s390_vcpu_sie_inhibited(vcpu)) {

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)

				goto skip_sie;

			goto xfer_to_guest_mode_check;

		}

		guest_timing_enter_irqoff();

		rc = kvm_s390_enter_exit_sie(scb_s, vcpu->run->s.regs.gprs, vsie_page->gmap->asce);

		guest_timing_exit_irqoff();

		local_irq_enable();

	}



skip_sie:

	barrier();

	vcpu->arch.sie_block->prog0c &= ~PROG_IN_SIE;
@@ -1345,13 +1356,11 @@ static int vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) 
		 * but rewind the PSW to re-enter SIE once that's completed

		 * instead of passing a "no action" intercept to the guest.

		 */

		if (signal_pending(current) ||

		    kvm_s390_vcpu_has_irq(vcpu, 0) ||

		if (kvm_s390_vcpu_has_irq(vcpu, 0) ||

		    kvm_s390_vcpu_sie_inhibited(vcpu)) {

			kvm_s390_rewind_psw(vcpu, 4);

			break;

		}

		cond_resched();

	}



	if (rc == -EFAULT) {
@@ -1483,8 +1492,7 @@ int kvm_s390_handle_vsie(struct kvm_vcpu *vcpu) 
	if (unlikely(scb_addr & 0x1ffUL))

		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);



	if (signal_pending(current) || kvm_s390_vcpu_has_irq(vcpu, 0) ||

	    kvm_s390_vcpu_sie_inhibited(vcpu)) {

	if (kvm_s390_vcpu_has_irq(vcpu, 0) || kvm_s390_vcpu_sie_inhibited(vcpu)) {

		kvm_s390_rewind_psw(vcpu, 4);

		return 0;

	}