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KVM: s390: vsie: Avoid injecting machine check on signal 

The recent XFER_TO_GUEST_WORK change resulted in a situation, where the
vsie code would interpret a signal during work as a machine check during
SIE as both use the EINTR return code.
The exit_reason of the sie64a function has nothing to do with the
kvm_run exit_reason. Rename it and define a specific code for machine
checks instead of abusing -EINTR.
rename exit_reason into sie_return to avoid the naming conflict
and change the code flow in vsie.c to have a separate variable for rc
and sie_return.

Fixes: 2bd1337a12 ("KVM: s390: Use generic VIRT_XFER_TO_GUEST_WORK functions")
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
master
Christian Borntraeger 2026-03-16 13:13:17 +01:00
parent 1ca90f4ae5
commit ab5119735e
7 changed files with 22 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/s390/include/asm/kvm_host.h
View File

@ -710,6 +710,9 @@ void kvm_arch_crypto_clear_masks(struct kvm *kvm);
void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm,
unsigned long *aqm, unsigned long *adm);
#define SIE64_RETURN_NORMAL 0
#define SIE64_RETURN_MCCK 1
int __sie64a(phys_addr_t sie_block_phys, struct kvm_s390_sie_block *sie_block, u64 *rsa,
unsigned long gasce);

2
arch/s390/include/asm/stacktrace.h
View File

@ -62,7 +62,7 @@ struct stack_frame {
struct {
unsigned long sie_control_block;
unsigned long sie_savearea;
unsigned long sie_reason;
unsigned long sie_return;
unsigned long sie_flags;
unsigned long sie_control_block_phys;
unsigned long sie_guest_asce;

2
arch/s390/kernel/asm-offsets.c
View File

@ -63,7 +63,7 @@ int main(void)
OFFSET(__SF_EMPTY, stack_frame, empty[0]);
OFFSET(__SF_SIE_CONTROL, stack_frame, sie_control_block);
OFFSET(__SF_SIE_SAVEAREA, stack_frame, sie_savearea);
OFFSET(__SF_SIE_REASON, stack_frame, sie_reason);
OFFSET(__SF_SIE_RETURN, stack_frame, sie_return);
OFFSET(__SF_SIE_FLAGS, stack_frame, sie_flags);
OFFSET(__SF_SIE_CONTROL_PHYS, stack_frame, sie_control_block_phys);
OFFSET(__SF_SIE_GUEST_ASCE, stack_frame, sie_guest_asce);

4
arch/s390/kernel/entry.S
View File

@ -200,7 +200,7 @@ SYM_FUNC_START(__sie64a)
stg %r3,__SF_SIE_CONTROL(%r15) # ...and virtual addresses
stg %r4,__SF_SIE_SAVEAREA(%r15) # save guest register save area
stg %r5,__SF_SIE_GUEST_ASCE(%r15) # save guest asce
xc __SF_SIE_REASON(8,%r15),__SF_SIE_REASON(%r15) # reason code = 0
xc __SF_SIE_RETURN(8,%r15),__SF_SIE_RETURN(%r15) # return code = 0
mvc __SF_SIE_FLAGS(8,%r15),__TI_flags(%r14) # copy thread flags
lmg %r0,%r13,0(%r4) # load guest gprs 0-13
mvi __TI_sie(%r14),1
@ -237,7 +237,7 @@ SYM_INNER_LABEL(sie_exit, SYM_L_GLOBAL)
xgr %r4,%r4
xgr %r5,%r5
lmg %r6,%r14,__SF_GPRS(%r15) # restore kernel registers
lg %r2,__SF_SIE_REASON(%r15) # return exit reason code
lg %r2,__SF_SIE_RETURN(%r15) # return sie return code
BR_EX %r14
SYM_FUNC_END(__sie64a)
EXPORT_SYMBOL(__sie64a)

4
arch/s390/kernel/nmi.c
View File

@ -487,8 +487,8 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK);
if (test_cpu_flag(CIF_MCCK_GUEST) &&
(mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) {
/* Set exit reason code for host's later handling */
*((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR;
/* Set sie return code for host's later handling */
((struct stack_frame *)regs->gprs[15])->sie_return = SIE64_RETURN_MCCK;
}
clear_cpu_flag(CIF_MCCK_GUEST);

15
arch/s390/kvm/kvm-s390.c
View File

@ -4617,7 +4617,7 @@ static int vcpu_post_run_handle_fault(struct kvm_vcpu *vcpu)
return 0;
}
static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason)
static int vcpu_post_run(struct kvm_vcpu *vcpu, int sie_return)
{
struct mcck_volatile_info *mcck_info;
struct sie_page *sie_page;
@ -4633,13 +4633,14 @@ static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason)
vcpu->run->s.regs.gprs[14] = vcpu->arch.sie_block->gg14;
vcpu->run->s.regs.gprs[15] = vcpu->arch.sie_block->gg15;
if (exit_reason == -EINTR) {
if (sie_return == SIE64_RETURN_MCCK) {
sie_page = container_of(vcpu->arch.sie_block,
struct sie_page, sie_block);
mcck_info = &sie_page->mcck_info;
kvm_s390_reinject_machine_check(vcpu, mcck_info);
return 0;
}
WARN_ON_ONCE(sie_return != SIE64_RETURN_NORMAL);
if (vcpu->arch.sie_block->icptcode > 0) {
rc = kvm_handle_sie_intercept(vcpu);
@ -4678,7 +4679,7 @@ int noinstr kvm_s390_enter_exit_sie(struct kvm_s390_sie_block *scb,
#define PSW_INT_MASK (PSW_MASK_EXT | PSW_MASK_IO | PSW_MASK_MCHECK)
static int __vcpu_run(struct kvm_vcpu *vcpu)
{
int rc, exit_reason;
int rc, sie_return;
struct sie_page *sie_page = (struct sie_page *)vcpu->arch.sie_block;
/*
@ -4718,9 +4719,9 @@ xfer_to_guest_mode_check:
guest_timing_enter_irqoff();
__disable_cpu_timer_accounting(vcpu);
exit_reason = kvm_s390_enter_exit_sie(vcpu->arch.sie_block,
vcpu->run->s.regs.gprs,
vcpu->arch.gmap->asce.val);
sie_return = kvm_s390_enter_exit_sie(vcpu->arch.sie_block,
vcpu->run->s.regs.gprs,
vcpu->arch.gmap->asce.val);
__enable_cpu_timer_accounting(vcpu);
guest_timing_exit_irqoff();
@ -4743,7 +4744,7 @@ xfer_to_guest_mode_check:
}
kvm_vcpu_srcu_read_lock(vcpu);
rc = vcpu_post_run(vcpu, exit_reason);
rc = vcpu_post_run(vcpu, sie_return);
if (rc || guestdbg_exit_pending(vcpu)) {
kvm_vcpu_srcu_read_unlock(vcpu);
break;

7
arch/s390/kvm/vsie.c
View File

@ -1122,6 +1122,7 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page, struc
{
struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
unsigned long sie_return = SIE64_RETURN_NORMAL;
int guest_bp_isolation;
int rc = 0;
@ -1163,7 +1164,7 @@ xfer_to_guest_mode_check:
goto xfer_to_guest_mode_check;
}
guest_timing_enter_irqoff();
rc = kvm_s390_enter_exit_sie(scb_s, vcpu->run->s.regs.gprs, sg->asce.val);
sie_return = kvm_s390_enter_exit_sie(scb_s, vcpu->run->s.regs.gprs, sg->asce.val);
guest_timing_exit_irqoff();
local_irq_enable();
}
@ -1178,11 +1179,13 @@ skip_sie:
kvm_vcpu_srcu_read_lock(vcpu);
if (rc == -EINTR) {
if (sie_return == SIE64_RETURN_MCCK) {
kvm_s390_reinject_machine_check(vcpu, &vsie_page->mcck_info);
return 0;
}
WARN_ON_ONCE(sie_return != SIE64_RETURN_NORMAL);
if (rc > 0)
rc = 0; /* we could still have an icpt */
else if (current->thread.gmap_int_code)