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authorCarsten Otte <cotte@de.ibm.com>2009-05-12 17:21:48 +0200
committerAvi Kivity <avi@redhat.com>2009-06-10 11:48:55 +0300
commit2668dab794272f0898491acaf1e77e9a005abc0f (patch)
treeaeb223675bed96f0b5fc15bc3f9474381fe28364 /arch
parent58f8ac279a8c46eb0a3193edd521ed2e41c4f914 (diff)
KVM: s390: Fix memory slot versus run - v3
This patch fixes an incorrectness in the kvm backend for s390. In case virtual cpus are being created before the corresponding memory slot is being registered, we need to update the sie control blocks for the virtual cpus. *updates in v3* In consideration of the s390 memslot constraints locking was changed to trylock. These locks should never be held, as vcpu's can't run without the single memslot we just assign when running this code. To ensure this never deadlocks in case other code changes the code uses trylocks and bail out if it can't get all locks. Additionally most of the discussed special conditions for s390 like only one memslot and no user_alloc are now checked for validity in kvm_arch_set_memory_region. Reported-by: Mijo Safradin <mijo@linux.vnet.ibm.com> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Christian Ehrhardt <ehrhardt@de.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/s390/kvm/kvm-s390.c36
1 files changed, 31 insertions, 5 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index f4d56e9939c..86567e174fd 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -657,6 +657,8 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
struct kvm_memory_slot old,
int user_alloc)
{
+ int i;
+
/* A few sanity checks. We can have exactly one memory slot which has
to start at guest virtual zero and which has to be located at a
page boundary in userland and which has to end at a page boundary.
@@ -664,7 +666,7 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
vmas. It is okay to mmap() and munmap() stuff in this slot after
doing this call at any time */
- if (mem->slot)
+ if (mem->slot || kvm->arch.guest_memsize)
return -EINVAL;
if (mem->guest_phys_addr)
@@ -676,15 +678,39 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
if (mem->memory_size & (PAGE_SIZE - 1))
return -EINVAL;
+ if (!user_alloc)
+ return -EINVAL;
+
+ /* lock all vcpus */
+ for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+ if (!kvm->vcpus[i])
+ continue;
+ if (!mutex_trylock(&kvm->vcpus[i]->mutex))
+ goto fail_out;
+ }
+
kvm->arch.guest_origin = mem->userspace_addr;
kvm->arch.guest_memsize = mem->memory_size;
- /* FIXME: we do want to interrupt running CPUs and update their memory
- configuration now to avoid race conditions. But hey, changing the
- memory layout while virtual CPUs are running is usually bad
- programming practice. */
+ /* update sie control blocks, and unlock all vcpus */
+ for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+ if (kvm->vcpus[i]) {
+ kvm->vcpus[i]->arch.sie_block->gmsor =
+ kvm->arch.guest_origin;
+ kvm->vcpus[i]->arch.sie_block->gmslm =
+ kvm->arch.guest_memsize +
+ kvm->arch.guest_origin +
+ VIRTIODESCSPACE - 1ul;
+ mutex_unlock(&kvm->vcpus[i]->mutex);
+ }
+ }
return 0;
+
+fail_out:
+ for (; i >= 0; i--)
+ mutex_unlock(&kvm->vcpus[i]->mutex);
+ return -EINVAL;
}
void kvm_arch_flush_shadow(struct kvm *kvm)