shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-07 03:15:31 +09:00
Code Issues Packages Projects Releases Wiki Activity

ANDROID: KVM: arm64: Push shadow table locking up to callers

Browse Source 
The pKVM shadow table is protected by 'shadow_lock', however this lock
is only taken across relatively fine-grained calls when inserting and
removing entries from the table. This poses a problem for higher-level
functions such as __pkvm_init_shadow(), where a partially-initialised
shadow entry is made transiently visibly to get_shadow_vcpu() and could
potentially be loaded in an inconsistent state by another CPU.

Push the locking out of the insert/remove functions and up into
__pkvm_{init,teardown}_shadow() so that the shadow state always appears
to be consistent as long as the lock is held.

Bug: 216808671
Signed-off-by: Will Deacon <willdeacon@google.com>
Change-Id: I74c563a539c1ce35f5da86a8281e47c7d435bd27
This commit is contained in:
Will Deacon
2022-03-10 13:19:28 +00:00
committed by Quentin Perret
parent 2aca919c87
commit c7bd5ae906
1 changed files with 18 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files

50
arch/arm64/kvm/hyp/nvhe/pkvm.c
View File

@@ -439,7 +439,7 @@ static int init_shadow_structs(struct kvm *kvm, struct kvm_shadow_vm *vm,
return 0;
}
static bool exists_shadow(struct kvm *host_kvm)
static bool __exists_shadow(struct kvm *host_kvm)
{
int i;
int num_checked = 0;
@@ -463,13 +463,15 @@ static bool exists_shadow(struct kvm *host_kvm)
* Return a unique handle to the protected VM on success,
* negative error code on failure.
*/
static int __insert_shadow_table(struct kvm *kvm, struct kvm_shadow_vm *vm,
size_t shadow_size)
static int insert_shadow_table(struct kvm *kvm, struct kvm_shadow_vm *vm,
size_t shadow_size)
{
struct kvm_s2_mmu *mmu = &vm->arch.mmu;
int shadow_handle;
int vmid;
hyp_assert_lock_held(&shadow_lock);
if (unlikely(num_shadow_entries >= KVM_MAX_PVMS))
return -ENOMEM;
@@ -481,7 +483,7 @@ static int __insert_shadow_table(struct kvm *kvm, struct kvm_shadow_vm *vm,
return -EINVAL;
/* Check that a shadow hasn't been created before for this host KVM. */
if (unlikely(exists_shadow(kvm)))
if (unlikely(__exists_shadow(kvm)))
return -EEXIST;
/* Find the next free entry in the shadow table. */
@@ -509,32 +511,14 @@ static int __insert_shadow_table(struct kvm *kvm, struct kvm_shadow_vm *vm,
return shadow_handle;
}
static int insert_shadow_table(struct kvm *kvm, struct kvm_shadow_vm *vm,
size_t shadow_size)
{
int ret;
hyp_spin_lock(&shadow_lock);
ret = __insert_shadow_table(kvm, vm, shadow_size);
hyp_spin_unlock(&shadow_lock);
return ret;
}
/*
* Deallocate and remove the shadow table entry corresponding to the handle.
*/
static void __remove_shadow_table(int shadow_handle)
{
shadow_table[shadow_handle_to_index(shadow_handle)] = NULL;
num_shadow_entries--;
}
static void remove_shadow_table(int shadow_handle)
{
hyp_spin_lock(&shadow_lock);
__remove_shadow_table(shadow_handle);
hyp_spin_unlock(&shadow_lock);
hyp_assert_lock_held(&shadow_lock);
shadow_table[shadow_handle_to_index(shadow_handle)] = NULL;
num_shadow_entries--;
}
static size_t pkvm_get_shadow_size(int num_vcpus)
@@ -633,27 +617,29 @@ int __pkvm_init_shadow(struct kvm *kvm,
if (ret)
goto err_remove_pgd;
/* Add the entry to the shadow table. */
ret = insert_shadow_table(kvm, vm, shadow_size);
ret = init_shadow_structs(kvm, vm, pgd, nr_vcpus);
if (ret < 0)
goto err_unpin_host_vcpus;
ret = init_shadow_structs(kvm, vm, pgd, nr_vcpus);
/* Add the entry to the shadow table. */
hyp_spin_lock(&shadow_lock);
ret = insert_shadow_table(kvm, vm, shadow_size);
if (ret < 0)
goto err_remove_shadow_table;
goto err_unlock_unpin_host_vcpus;
ret = kvm_guest_prepare_stage2(vm, pgd);
if (ret)
goto err_remove_shadow_table;
hyp_spin_unlock(&shadow_lock);
return vm->shadow_handle;
err_remove_shadow_table:
remove_shadow_table(vm->shadow_handle);
err_unlock_unpin_host_vcpus:
hyp_spin_unlock(&shadow_lock);
err_unpin_host_vcpus:
unpin_host_vcpus(vm->shadow_vcpus, nr_vcpus);
err_remove_pgd:
WARN_ON(__pkvm_hyp_donate_host(hyp_virt_to_pfn(pgd), nr_pgd_pages));
@@ -692,7 +678,7 @@ int __pkvm_teardown_shadow(int shadow_handle)
goto err_unlock;
}
__remove_shadow_table(shadow_handle);
remove_shadow_table(shadow_handle);
hyp_spin_unlock(&shadow_lock);
/* Reclaim guest pages, and page-table pages */