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Merge tag 'kvm-memslots-6.14' of https://github.com/kvm-x86/linux into HEAD

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KVM kvm_set_memory_region() cleanups and hardening for 6.14:

 - Add proper lockdep assertions when setting memory regions.

 - Add a dedicated API for setting KVM-internal memory regions.

 - Explicitly disallow all flags for KVM-internal memory regions.
This commit is contained in:
Paolo Bonzini
2025-01-20 06:36:14 -05:00
parent 5cf32aff20 0cc3cb2151
commit 4e4f38f84e
3 changed files with 21 additions and 27 deletions
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7
arch/x86/kvm/x86.c
View File

@@ -12800,7 +12800,8 @@ void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
struct kvm_memslots *slots = kvm_memslots(kvm);
struct kvm_memory_slot *slot;
/* Called with kvm->slots_lock held. */
lockdep_assert_held(&kvm->slots_lock);
if (WARN_ON(id >= KVM_MEM_SLOTS_NUM))
return ERR_PTR_USR(-EINVAL);
@@ -12833,7 +12834,7 @@ void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
m.guest_phys_addr = gpa;
m.userspace_addr = hva;
m.memory_size = size;
r = __kvm_set_memory_region(kvm, &m);
r = kvm_set_internal_memslot(kvm, &m);
if (r < 0)
return ERR_PTR_USR(r);
}
@@ -12934,7 +12935,7 @@ static int kvm_alloc_memslot_metadata(struct kvm *kvm,
/*
* Clear out the previous array pointers for the KVM_MR_MOVE case. The
* old arrays will be freed by __kvm_set_memory_region() if installing
* old arrays will be freed by kvm_set_memory_region() if installing
* the new memslot is successful.
*/
memset(&slot->arch, 0, sizeof(slot->arch));

8
include/linux/kvm_host.h
View File

@@ -1183,7 +1183,7 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn
* -- just change its flags
*
* Since flags can be changed by some of these operations, the following
* differentiation is the best we can do for __kvm_set_memory_region():
* differentiation is the best we can do for kvm_set_memory_region():
*/
enum kvm_mr_change {
KVM_MR_CREATE,
@@ -1192,10 +1192,8 @@ enum kvm_mr_change {
KVM_MR_FLAGS_ONLY,
};
int kvm_set_memory_region(struct kvm *kvm,
const struct kvm_userspace_memory_region2 *mem);
int __kvm_set_memory_region(struct kvm *kvm,
const struct kvm_userspace_memory_region2 *mem);
int kvm_set_internal_memslot(struct kvm *kvm,
const struct kvm_userspace_memory_region2 *mem);
void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot);
void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen);
int kvm_arch_prepare_memory_region(struct kvm *kvm,

33
virt/kvm/kvm_main.c
View File

@@ -1926,16 +1926,8 @@ static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id,
return false;
}
/*
* Allocate some memory and give it an address in the guest physical address
* space.
*
* Discontiguous memory is allowed, mostly for framebuffers.
*
* Must be called holding kvm->slots_lock for write.
*/
int __kvm_set_memory_region(struct kvm *kvm,
const struct kvm_userspace_memory_region2 *mem)
static int kvm_set_memory_region(struct kvm *kvm,
const struct kvm_userspace_memory_region2 *mem)
{
struct kvm_memory_slot *old, *new;
struct kvm_memslots *slots;
@@ -1945,6 +1937,8 @@ int __kvm_set_memory_region(struct kvm *kvm,
int as_id, id;
int r;
lockdep_assert_held(&kvm->slots_lock);
r = check_memory_region_flags(kvm, mem);
if (r)
return r;
@@ -2056,19 +2050,19 @@ int __kvm_set_memory_region(struct kvm *kvm,
kfree(new);
return r;
}
EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
int kvm_set_memory_region(struct kvm *kvm,
const struct kvm_userspace_memory_region2 *mem)
int kvm_set_internal_memslot(struct kvm *kvm,
const struct kvm_userspace_memory_region2 *mem)
{
int r;
if (WARN_ON_ONCE(mem->slot < KVM_USER_MEM_SLOTS))
return -EINVAL;
mutex_lock(&kvm->slots_lock);
r = __kvm_set_memory_region(kvm, mem);
mutex_unlock(&kvm->slots_lock);
return r;
if (WARN_ON_ONCE(mem->flags))
return -EINVAL;
return kvm_set_memory_region(kvm, mem);
}
EXPORT_SYMBOL_GPL(kvm_set_memory_region);
EXPORT_SYMBOL_GPL(kvm_set_internal_memslot);
static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region2 *mem)
@@ -2076,6 +2070,7 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
if ((u16)mem->slot >= KVM_USER_MEM_SLOTS)
return -EINVAL;
guard(mutex)(&kvm->slots_lock);
return kvm_set_memory_region(kvm, mem);
}