| Message ID | 20200327094339.26111-1-borntraeger@de.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | s390x/pv: Retry ioctls on -EINTR | expand |
On 27.03.20 10:43, Christian Borntraeger wrote: > PV_ENABLE (and maybe others) might return -EINTR when a signal is > pending. Let us retry the ioctl in that case. > > Fixes: 4d226deafc44 ("s390x: protvirt: Support unpack facility") > Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com> > Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com> > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> > --- > hw/s390x/pv.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/hw/s390x/pv.c b/hw/s390x/pv.c > index 8cf5cd2c9b..2758b02c96 100644 > --- a/hw/s390x/pv.c > +++ b/hw/s390x/pv.c > @@ -23,7 +23,11 @@ static int __s390_pv_cmd(uint32_t cmd, const char *cmdname, void *data) > .cmd = cmd, > .data = (uint64_t)data, > }; > - int rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd); > + int rc; > + > + do { > + rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd); > + } while (rc == -EINTR); > > if (rc) { > error_report("KVM PV command %d (%s) failed: header rc %x rrc %x " > I fail to see where that is triggered in the kernel. t480s: ~/git/linux/arch/s390/kvm (HEAD losgelöst bei next/master) $ git grep "EINTR" kvm-s390.c: if (exit_reason == -EINTR) { kvm-s390.c: return -EINTR; kvm-s390.c: rc = -EINTR; vsie.c: if (rc == -EINTR) { Can you help me out? Is that documented?
On 3/27/20 10:43 AM, Christian Borntraeger wrote: > PV_ENABLE (and maybe others) might return -EINTR when a signal is > pending. Let us retry the ioctl in that case. > > Fixes: 4d226deafc44 ("s390x: protvirt: Support unpack facility") > Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com> > Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com> > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com> > --- > hw/s390x/pv.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/hw/s390x/pv.c b/hw/s390x/pv.c > index 8cf5cd2c9b..2758b02c96 100644 > --- a/hw/s390x/pv.c > +++ b/hw/s390x/pv.c > @@ -23,7 +23,11 @@ static int __s390_pv_cmd(uint32_t cmd, const char *cmdname, void *data) > .cmd = cmd, > .data = (uint64_t)data, > }; > - int rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd); > + int rc; > + > + do { > + rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd); Double whitespace after rc. > + } while (rc == -EINTR); > > if (rc) { > error_report("KVM PV command %d (%s) failed: header rc %x rrc %x " >
On 27.03.20 10:49, David Hildenbrand wrote: > On 27.03.20 10:43, Christian Borntraeger wrote: >> PV_ENABLE (and maybe others) might return -EINTR when a signal is >> pending. Let us retry the ioctl in that case. >> >> Fixes: 4d226deafc44 ("s390x: protvirt: Support unpack facility") >> Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com> >> Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com> >> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> >> --- >> hw/s390x/pv.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/hw/s390x/pv.c b/hw/s390x/pv.c >> index 8cf5cd2c9b..2758b02c96 100644 >> --- a/hw/s390x/pv.c >> +++ b/hw/s390x/pv.c >> @@ -23,7 +23,11 @@ static int __s390_pv_cmd(uint32_t cmd, const char *cmdname, void *data) >> .cmd = cmd, >> .data = (uint64_t)data, >> }; >> - int rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd); >> + int rc; >> + >> + do { >> + rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd); >> + } while (rc == -EINTR); >> >> if (rc) { >> error_report("KVM PV command %d (%s) failed: header rc %x rrc %x " >> > > I fail to see where that is triggered in the kernel. > > t480s: ~/git/linux/arch/s390/kvm (HEAD losgelöst bei next/master) $ git > grep "EINTR" > kvm-s390.c: if (exit_reason == -EINTR) { > kvm-s390.c: return -EINTR; > kvm-s390.c: rc = -EINTR; > vsie.c: if (rc == -EINTR) { > > > Can you help me out? Is that documented? It is related to the kernel patch. ksm_madvise->unmerge_ksm_pages has if (signal_pending(current)) err = -ERESTARTSYS; entry.S will retranslate ERESTARTSYS into -EINTR.
On 27.03.20 10:54, Christian Borntraeger wrote: > > > On 27.03.20 10:49, David Hildenbrand wrote: >> On 27.03.20 10:43, Christian Borntraeger wrote: >>> PV_ENABLE (and maybe others) might return -EINTR when a signal is >>> pending. Let us retry the ioctl in that case. >>> >>> Fixes: 4d226deafc44 ("s390x: protvirt: Support unpack facility") >>> Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com> >>> Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com> >>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> >>> --- >>> hw/s390x/pv.c | 6 +++++- >>> 1 file changed, 5 insertions(+), 1 deletion(-) >>> >>> diff --git a/hw/s390x/pv.c b/hw/s390x/pv.c >>> index 8cf5cd2c9b..2758b02c96 100644 >>> --- a/hw/s390x/pv.c >>> +++ b/hw/s390x/pv.c >>> @@ -23,7 +23,11 @@ static int __s390_pv_cmd(uint32_t cmd, const char *cmdname, void *data) >>> .cmd = cmd, >>> .data = (uint64_t)data, >>> }; >>> - int rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd); >>> + int rc; >>> + >>> + do { >>> + rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd); >>> + } while (rc == -EINTR); >>> >>> if (rc) { >>> error_report("KVM PV command %d (%s) failed: header rc %x rrc %x " >>> >> >> I fail to see where that is triggered in the kernel. >> >> t480s: ~/git/linux/arch/s390/kvm (HEAD losgelöst bei next/master) $ git >> grep "EINTR" >> kvm-s390.c: if (exit_reason == -EINTR) { >> kvm-s390.c: return -EINTR; >> kvm-s390.c: rc = -EINTR; >> vsie.c: if (rc == -EINTR) { >> >> >> Can you help me out? Is that documented? > > It is related to the kernel patch. > ksm_madvise->unmerge_ksm_pages has > > if (signal_pending(current)) > err = -ERESTARTSYS; > > > entry.S will retranslate ERESTARTSYS into -EINTR. That's valuable information that should go into the patch description. Also, the documentation should be updated to reflect this. Not obvious :)
>> I fail to see where that is triggered in the kernel. >> >> t480s: ~/git/linux/arch/s390/kvm (HEAD losgelöst bei next/master) $ git >> grep "EINTR" >> kvm-s390.c: if (exit_reason == -EINTR) { >> kvm-s390.c: return -EINTR; >> kvm-s390.c: rc = -EINTR; >> vsie.c: if (rc == -EINTR) { >> >> >> Can you help me out? Is that documented? > > It is related to the kernel patch. > ksm_madvise->unmerge_ksm_pages has > > if (signal_pending(current)) > err = -ERESTARTSYS; > > > entry.S will retranslate ERESTARTSYS into -EINTR. > In the end both patches fixes an odd-ball case. Marc had a test running that in parallel started guests and randomly killing QEMUs with pkill. The QEMUs did end with qemu-system-s390x: KVM PV command 0 (KVM_PV_ENABLE) failed: header rc 0 rrc 0 IOCTL rc: -12 instead of qemu-system-s390x: terminating on signal 15 from pid 26495 (pkill)
On 27.03.20 10:58, Christian Borntraeger wrote: >>> I fail to see where that is triggered in the kernel. >>> >>> t480s: ~/git/linux/arch/s390/kvm (HEAD losgelöst bei next/master) $ git >>> grep "EINTR" >>> kvm-s390.c: if (exit_reason == -EINTR) { >>> kvm-s390.c: return -EINTR; >>> kvm-s390.c: rc = -EINTR; >>> vsie.c: if (rc == -EINTR) { >>> >>> >>> Can you help me out? Is that documented? >> >> It is related to the kernel patch. >> ksm_madvise->unmerge_ksm_pages has >> >> if (signal_pending(current)) >> err = -ERESTARTSYS; >> >> >> entry.S will retranslate ERESTARTSYS into -EINTR. >> > > In the end both patches fixes an odd-ball case. Marc had a test running > that in parallel started guests and randomly killing QEMUs with pkill. > The QEMUs did end with > > qemu-system-s390x: KVM PV command 0 (KVM_PV_ENABLE) failed: header rc 0 rrc 0 IOCTL rc: -12 > > instead of > > qemu-system-s390x: terminating on signal 15 from pid 26495 (pkill) > I guess the same can happen with a qemu_cpu_kick(), just that the BQL protects us from that to happen concurrently.
diff --git a/hw/s390x/pv.c b/hw/s390x/pv.c index 8cf5cd2c9b..2758b02c96 100644 --- a/hw/s390x/pv.c +++ b/hw/s390x/pv.c @@ -23,7 +23,11 @@ static int __s390_pv_cmd(uint32_t cmd, const char *cmdname, void *data) .cmd = cmd, .data = (uint64_t)data, }; - int rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd); + int rc; + + do { + rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd); + } while (rc == -EINTR); if (rc) { error_report("KVM PV command %d (%s) failed: header rc %x rrc %x "
PV_ENABLE (and maybe others) might return -EINTR when a signal is pending. Let us retry the ioctl in that case. Fixes: 4d226deafc44 ("s390x: protvirt: Support unpack facility") Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com> Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> --- hw/s390x/pv.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)