admin/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2025-12-07 20:06:24 +00:00
Code Issues Packages Projects Releases Wiki Activity

KVM: s390: Use generic VIRT_XFER_TO_GUEST_WORK functions

Browse Source 
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>
This commit is contained in:
Andrew Donnellan
2025-11-26 16:33:12 +11:00
committed by Janosch Frank
parent d0139059e3
commit 2bd1337a12
3 changed files with 32 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
arch/s390/kvm/Kconfig
View File

@@ -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

25
arch/s390/kvm/kvm-s390.c
View File

@@ -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;
}

18
arch/s390/kvm/vsie.c
View File

@@ -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;
}