| Message ID | 20230307140522.2311461-56-ardb@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Add support for LPA2 at stage1 and WXN | expand |
On 07/03/2023 14:05, Ard Biesheuvel wrote: > get_user_mapping_size() uses vabits_actual and CONFIG_PGTABLE_LEVELS to > provide the starting point for a table walk. This is fine for LVA, as > the number of translation levels is the same regardless of whether LVA > is enabled. However, with LPA2, this will no longer be the case, so > let's derive the number of levels from the number of VA bits directly. > > Signed-off-by: Ard Biesheuvel <ardb@kernel.org> > --- > arch/arm64/kvm/mmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index d64be7b5f6692e8b..4e7c0f9a9c286c09 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -663,7 +663,7 @@ static int get_user_mapping_size(struct kvm *kvm, u64 addr) > .pgd = (kvm_pteref_t)kvm->mm->pgd, > .ia_bits = vabits_actual, > .start_level = (KVM_PGTABLE_MAX_LEVELS - > - CONFIG_PGTABLE_LEVELS), > + ARM64_HW_PGTABLE_LEVELS(pgt.ia_bits)), > .mm_ops = &kvm_user_mm_ops, > }; > kvm_pte_t pte = 0; /* Keep GCC quiet... */ You have the problem here that the KVM library (which isn't LPA2 aware) is walking a kernel page table, which may now be in LPA2 format. I think this works out ok as long as there are no physical addresses above 48 bits in the page table. But otherwise, I doubt it works out very well...
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index d64be7b5f6692e8b..4e7c0f9a9c286c09 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -663,7 +663,7 @@ static int get_user_mapping_size(struct kvm *kvm, u64 addr) .pgd = (kvm_pteref_t)kvm->mm->pgd, .ia_bits = vabits_actual, .start_level = (KVM_PGTABLE_MAX_LEVELS - - CONFIG_PGTABLE_LEVELS), + ARM64_HW_PGTABLE_LEVELS(pgt.ia_bits)), .mm_ops = &kvm_user_mm_ops, }; kvm_pte_t pte = 0; /* Keep GCC quiet... */
get_user_mapping_size() uses vabits_actual and CONFIG_PGTABLE_LEVELS to provide the starting point for a table walk. This is fine for LVA, as the number of translation levels is the same regardless of whether LVA is enabled. However, with LPA2, this will no longer be the case, so let's derive the number of levels from the number of VA bits directly. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/arm64/kvm/mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)