| Message ID | 1526462314-19720-1-git-send-email-zhaoshenglong@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Ping? On 2018/5/16 17:18, Shannon Zhao wrote: > According to KVM commit 75d61fbc, it needs to delete the slot before > changing the KVM_MEM_READONLY flag. But QEMU commit 235e8982 only check > whether KVM_MEM_READONLY flag is set instead of changing. It doesn't > need to delete the slot if the KVM_MEM_READONLY flag is not changed. > > This fixes a issue that migrating a VM at the OVMF startup stage and > VM is executing the codes in rom. Between the deleting and adding the > slot in kvm_set_user_memory_region, there is a chance that guest access > rom and trap to KVM, then KVM can't find the corresponding memslot. > While KVM (on ARM) injects an abort to guest due to the broken hva, then > guest will get stuck. > > Signed-off-by: Shannon Zhao <zhaoshenglong@huawei.com> > --- > include/sysemu/kvm_int.h | 1 + > kvm-all.c | 6 +++--- > 2 files changed, 4 insertions(+), 3 deletions(-) > > diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h > index 888557a..f838412 100644 > --- a/include/sysemu/kvm_int.h > +++ b/include/sysemu/kvm_int.h > @@ -20,6 +20,7 @@ typedef struct KVMSlot > void *ram; > int slot; > int flags; > + int old_flags; > } KVMSlot; > > typedef struct KVMMemoryListener { > diff --git a/kvm-all.c b/kvm-all.c > index 2515a23..de8250e 100644 > --- a/kvm-all.c > +++ b/kvm-all.c > @@ -252,7 +252,7 @@ static int kvm_set_user_memory_region(KVMMemoryListener *kml, KVMSlot *slot) > mem.userspace_addr = (unsigned long)slot->ram; > mem.flags = slot->flags; > > - if (slot->memory_size && mem.flags & KVM_MEM_READONLY) { > + if (slot->memory_size && (mem.flags ^ slot->old_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; > @@ -376,11 +376,11 @@ static int kvm_slot_update_flags(KVMMemoryListener *kml, KVMSlot *mem, > { > int old_flags; > > - old_flags = mem->flags; > + mem->old_flags = mem->flags; > mem->flags = kvm_mem_flags(mr); > > /* If nothing changed effectively, no need to issue ioctl */ > - if (mem->flags == old_flags) { > + if (mem->flags == mem->old_flags) { > return 0; > } > >
diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h index 888557a..f838412 100644 --- a/include/sysemu/kvm_int.h +++ b/include/sysemu/kvm_int.h @@ -20,6 +20,7 @@ typedef struct KVMSlot void *ram; int slot; int flags; + int old_flags; } KVMSlot; typedef struct KVMMemoryListener { diff --git a/kvm-all.c b/kvm-all.c index 2515a23..de8250e 100644 --- a/kvm-all.c +++ b/kvm-all.c @@ -252,7 +252,7 @@ static int kvm_set_user_memory_region(KVMMemoryListener *kml, KVMSlot *slot) mem.userspace_addr = (unsigned long)slot->ram; mem.flags = slot->flags; - if (slot->memory_size && mem.flags & KVM_MEM_READONLY) { + if (slot->memory_size && (mem.flags ^ slot->old_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; @@ -376,11 +376,11 @@ static int kvm_slot_update_flags(KVMMemoryListener *kml, KVMSlot *mem, { int old_flags; - old_flags = mem->flags; + mem->old_flags = mem->flags; mem->flags = kvm_mem_flags(mr); /* If nothing changed effectively, no need to issue ioctl */ - if (mem->flags == old_flags) { + if (mem->flags == mem->old_flags) { return 0; }
According to KVM commit 75d61fbc, it needs to delete the slot before changing the KVM_MEM_READONLY flag. But QEMU commit 235e8982 only check whether KVM_MEM_READONLY flag is set instead of changing. It doesn't need to delete the slot if the KVM_MEM_READONLY flag is not changed. This fixes a issue that migrating a VM at the OVMF startup stage and VM is executing the codes in rom. Between the deleting and adding the slot in kvm_set_user_memory_region, there is a chance that guest access rom and trap to KVM, then KVM can't find the corresponding memslot. While KVM (on ARM) injects an abort to guest due to the broken hva, then guest will get stuck. Signed-off-by: Shannon Zhao <zhaoshenglong@huawei.com> --- include/sysemu/kvm_int.h | 1 + kvm-all.c | 6 +++--- 2 files changed, 4 insertions(+), 3 deletions(-)