| Message ID | 51A8485A.4000605@linux.vnet.ibm.com |
|---|---|
| State | New |
| Headers | show |
On Thu, May 30, 2013 at 11:51 PM, Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> wrote: > On 05/31/2013 12:50 AM, Jordan Justen wrote: >> On Thu, May 30, 2013 at 9:08 AM, Luiz Capitulino <lcapitulino@redhat.com> wrote: >>> On Thu, 30 May 2013 18:03:04 +0200 >>> Paolo Bonzini <pbonzini@redhat.com> wrote: >>> >>>> Il 30/05/2013 17:46, Luiz Capitulino ha scritto: >>>>> The culprit is commit: >>>>> >>>>> commit 235e8982ad393e5611cb892df54881c872eea9e1 >>>>> Author: Jordan Justen <jordan.l.justen@intel.com> >>>>> Date: Wed May 29 01:27:26 2013 -0700 >>>>> >>>>> kvm: support using KVM_MEM_READONLY flag for regions >>>>> >>>>> I'm running 3.9.2-200.fc18, btw. And, error checking is missing on the >>>>> first call to kvm_vm_ioctl(). >> >> As noted in the code, the first call is for KVM commit 75d61fbc. >> >> I'm not sure we want to fail if an error occurs when making that call. >> (I'm pretty sure we don't want to in fact.) >> >> Xiao, any thoughts? > > I have reproduced this bug, it seems that the bug is caused by double free > the memslot. After these change, it can boot the guest now. I think that I might have found that the flash memory had an issue with transitioning from flash to rom mode with code like this on the 3.8 kernel. I'll test it on 3.8 & 3.9. -Jordan > diff --git a/kvm-all.c b/kvm-all.c > index 8e7bbf8..405480e 100644 > --- a/kvm-all.c > +++ b/kvm-all.c > @@ -206,7 +206,8 @@ static int kvm_set_user_memory_region(KVMState *s, KVMSlot *slot) > if (s->migration_log) { > mem.flags |= KVM_MEM_LOG_DIRTY_PAGES; > } > - if (mem.flags & KVM_MEM_READONLY) { > + > + if (slot->memory_size && mem.flags & KVM_MEM_READONLY) { > /* Set the slot size to 0 before setting the slot to the desired > * value. This is needed based on KVM commit 75d61fbc. */ > mem.memory_size = 0; > >
On Fri, May 31, 2013 at 12:14 AM, Jordan Justen <jljusten@gmail.com> wrote: > On Thu, May 30, 2013 at 11:51 PM, Xiao Guangrong > <xiaoguangrong@linux.vnet.ibm.com> wrote: >> On 05/31/2013 12:50 AM, Jordan Justen wrote: >>> On Thu, May 30, 2013 at 9:08 AM, Luiz Capitulino <lcapitulino@redhat.com> wrote: >>>> On Thu, 30 May 2013 18:03:04 +0200 >>>> Paolo Bonzini <pbonzini@redhat.com> wrote: >>>> >>>>> Il 30/05/2013 17:46, Luiz Capitulino ha scritto: >>>>>> The culprit is commit: >>>>>> >>>>>> commit 235e8982ad393e5611cb892df54881c872eea9e1 >>>>>> Author: Jordan Justen <jordan.l.justen@intel.com> >>>>>> Date: Wed May 29 01:27:26 2013 -0700 >>>>>> >>>>>> kvm: support using KVM_MEM_READONLY flag for regions >>>>>> >>>>>> I'm running 3.9.2-200.fc18, btw. And, error checking is missing on the >>>>>> first call to kvm_vm_ioctl(). >>> >>> As noted in the code, the first call is for KVM commit 75d61fbc. >>> >>> I'm not sure we want to fail if an error occurs when making that call. >>> (I'm pretty sure we don't want to in fact.) >>> >>> Xiao, any thoughts? >> >> I have reproduced this bug, it seems that the bug is caused by double free >> the memslot. After these change, it can boot the guest now. > > I think that I might have found that the flash memory had an issue > with transitioning from flash to rom mode with code like this on the > 3.8 kernel. I'll test it on 3.8 & 3.9. Yes, the issue still occurs on 3.9, and even the "double free" doesn't work on 3.9 like it did on 3.8. This issue is a bit of a corner case for flash, but still important. I hope maybe Xiao might have time to help me understand it. (I'll email Xiao off-list about this.) But, for now, I think Xiao's patch will fix things for the non-flash case, and will not totally break flash support either. -Jordan
Il 31/05/2013 08:51, Xiao Guangrong ha scritto: > On 05/31/2013 12:50 AM, Jordan Justen wrote: >> On Thu, May 30, 2013 at 9:08 AM, Luiz Capitulino <lcapitulino@redhat.com> wrote: >>> On Thu, 30 May 2013 18:03:04 +0200 >>> Paolo Bonzini <pbonzini@redhat.com> wrote: >>> >>>> Il 30/05/2013 17:46, Luiz Capitulino ha scritto: >>>>> The culprit is commit: >>>>> >>>>> commit 235e8982ad393e5611cb892df54881c872eea9e1 >>>>> Author: Jordan Justen <jordan.l.justen@intel.com> >>>>> Date: Wed May 29 01:27:26 2013 -0700 >>>>> >>>>> kvm: support using KVM_MEM_READONLY flag for regions >>>>> >>>>> I'm running 3.9.2-200.fc18, btw. And, error checking is missing on the >>>>> first call to kvm_vm_ioctl(). >> >> As noted in the code, the first call is for KVM commit 75d61fbc. >> >> I'm not sure we want to fail if an error occurs when making that call. >> (I'm pretty sure we don't want to in fact.) >> >> Xiao, any thoughts? > > I have reproduced this bug, it seems that the bug is caused by double free > the memslot. After these change, it can boot the guest now. > > diff --git a/kvm-all.c b/kvm-all.c > index 8e7bbf8..405480e 100644 > --- a/kvm-all.c > +++ b/kvm-all.c > @@ -206,7 +206,8 @@ static int kvm_set_user_memory_region(KVMState *s, KVMSlot *slot) > if (s->migration_log) { > mem.flags |= KVM_MEM_LOG_DIRTY_PAGES; > } > - if (mem.flags & KVM_MEM_READONLY) { > + > + if (slot->memory_size && mem.flags & KVM_MEM_READONLY) { > /* Set the slot size to 0 before setting the slot to the desired > * value. This is needed based on KVM commit 75d61fbc. */ > mem.memory_size = 0; > > > > Thanks, can you submit it for uq/master? Please Cc kvm@vger.kernel.org too, and use [PATCH uq/master] as the prefix. Paolo
diff --git a/kvm-all.c b/kvm-all.c index 8e7bbf8..405480e 100644 --- a/kvm-all.c +++ b/kvm-all.c @@ -206,7 +206,8 @@ static int kvm_set_user_memory_region(KVMState *s, KVMSlot *slot) if (s->migration_log) { mem.flags |= KVM_MEM_LOG_DIRTY_PAGES; } - if (mem.flags & KVM_MEM_READONLY) { + + if (slot->memory_size && mem.flags & KVM_MEM_READONLY) { /* Set the slot size to 0 before setting the slot to the desired * value. This is needed based on KVM commit 75d61fbc. */ mem.memory_size = 0;