diff options
| author | Oliver Upton <oliver.upton@linux.dev> | 2022-11-18 18:22:22 +0000 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2022-11-22 13:05:53 +0000 |
| commit | 5e806c5812e8012a83496cf96bdba266b3aec428 (patch) | |
| tree | 5809e114c7d67e6e534fbf9c64c90a17474b4e63 /arch | |
| parent | b7833bf202e3068abb77c642a0843f696e9c8d38 (diff) | |
| download | linux-stable-5e806c5812e8012a83496cf96bdba266b3aec428.tar.gz linux-stable-5e806c5812e8012a83496cf96bdba266b3aec428.tar.bz2 linux-stable-5e806c5812e8012a83496cf96bdba266b3aec428.zip | |
KVM: arm64: Reject shared table walks in the hyp code
Exclusive table walks are the only supported table walk in the hyp, as
there is no construct like RCU available in the hypervisor code. Reject
any attempt to do a shared table walk by returning an error and allowing
the caller to clean up the mess.
Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221118182222.3932898-4-oliver.upton@linux.dev
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/kvm_pgtable.h | 17 | ||||
| -rw-r--r-- | arch/arm64/kvm/hyp/pgtable.c | 5 |
2 files changed, 19 insertions, 3 deletions
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index 4b6b52ebc11c..d5cb01f8dc06 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -229,7 +229,18 @@ static inline kvm_pte_t *kvm_dereference_pteref(struct kvm_pgtable_walker *walke return pteref; } -static inline void kvm_pgtable_walk_begin(struct kvm_pgtable_walker *walker) {} +static inline int kvm_pgtable_walk_begin(struct kvm_pgtable_walker *walker) +{ + /* + * Due to the lack of RCU (or a similar protection scheme), only + * non-shared table walkers are allowed in the hypervisor. + */ + if (walker->flags & KVM_PGTABLE_WALK_SHARED) + return -EPERM; + + return 0; +} + static inline void kvm_pgtable_walk_end(struct kvm_pgtable_walker *walker) {} static inline bool kvm_pgtable_walk_lock_held(void) @@ -247,10 +258,12 @@ static inline kvm_pte_t *kvm_dereference_pteref(struct kvm_pgtable_walker *walke return rcu_dereference_check(pteref, !(walker->flags & KVM_PGTABLE_WALK_SHARED)); } -static inline void kvm_pgtable_walk_begin(struct kvm_pgtable_walker *walker) +static inline int kvm_pgtable_walk_begin(struct kvm_pgtable_walker *walker) { if (walker->flags & KVM_PGTABLE_WALK_SHARED) rcu_read_lock(); + + return 0; } static inline void kvm_pgtable_walk_end(struct kvm_pgtable_walker *walker) diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index d6f3753cb87e..58dbe0ab567f 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -289,7 +289,10 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size, }; int r; - kvm_pgtable_walk_begin(walker); + r = kvm_pgtable_walk_begin(walker); + if (r) + return r; + r = _kvm_pgtable_walk(pgt, &walk_data); kvm_pgtable_walk_end(walker); |