Memory slot flags can be altered without changing other parameters of the slot. The read-only attribute is the only one the IOMMU cares about, so generate an un-map, re-map when this occurs. This also avoid unnecessarily re-mapping the slot when no IOMMU visible changes are made.
Signed-off-by: Alex Williamson <[email protected]> --- virt/kvm/kvm_main.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 5e709eb..3fec2cd 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -731,6 +731,7 @@ int __kvm_set_memory_region(struct kvm *kvm, struct kvm_memory_slot *slot; struct kvm_memory_slot old, new; struct kvm_memslots *slots = NULL, *old_memslots; + bool old_iommu_mapped; r = check_memory_region_flags(mem); if (r) @@ -772,6 +773,8 @@ int __kvm_set_memory_region(struct kvm *kvm, new.npages = npages; new.flags = mem->flags; + old_iommu_mapped = old.npages; + /* * Disallow changing a memory slot's size or changing anything about * zero sized slots that doesn't involve making them non-zero. @@ -835,6 +838,7 @@ int __kvm_set_memory_region(struct kvm *kvm, /* slot was deleted or moved, clear iommu mapping */ kvm_iommu_unmap_pages(kvm, &old); + old_iommu_mapped = false; /* From this point no new shadow pages pointing to a deleted, * or moved, memslot will be created. * @@ -863,11 +867,27 @@ int __kvm_set_memory_region(struct kvm *kvm, goto out_free; } - /* map new memory slot into the iommu */ + /* + * IOMMU mapping: New slots need to be mapped. Old slots need to be + * un-mapped and re-mapped if their base changes or if flags that the + * iommu cares about change (read-only). Base change unmapping is + * handled above with slot deletion, so we only unmap incompatible + * flags here. Anything else the iommu might care about for existing + * slots (size changes, userspace addr changes) is disallowed above, + * so any other attribute changes getting here can be skipped. + */ if (npages) { - r = kvm_iommu_map_pages(kvm, &new); - if (r) - goto out_slots; + if (old_iommu_mapped && + ((new.flags ^ old.flags) & KVM_MEM_READONLY)) { + kvm_iommu_unmap_pages(kvm, &old); + old_iommu_mapped = false; + } + + if (!old_iommu_mapped) { + r = kvm_iommu_map_pages(kvm, &new); + if (r) + goto out_slots; + } } /* actual memory is freed via old in kvm_free_physmem_slot below */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
