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SubjectRe: [PATCH v2 14/17] kvm: arm64: Switch to per VM IPA limit
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On 13/04/18 17:27, Punit Agrawal wrote:
> Hi Suzuki,
>
> I haven't had a chance to look at the code but noticed one issue below.
>
> Suzuki K Poulose <suzuki.poulose@arm.com> writes:
>
>> Now that we can manage the stage2 page table per VM, switch the
>> configuration details to per VM instance. We keep track of the
>> IPA bits, number of page table levels and the VTCR bits (which
>> depends on the IPA and the number of levels). While at it, remove
>> unused pgd_lock field from kvm_arch for arm64.
>>
>> Cc: Marc Zyngier <marc.zyngier@arm.com>
>> Cc: Christoffer Dall <cdall@kernel.org>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>> ---
>> arch/arm64/include/asm/kvm_host.h | 14 ++++++++++++--
>> arch/arm64/include/asm/kvm_mmu.h | 11 +++++++++--
>> arch/arm64/include/asm/stage2_pgtable.h | 1 -
>> arch/arm64/kvm/hyp/switch.c | 3 +--
>> virt/kvm/arm/mmu.c | 4 ++++
>> 5 files changed, 26 insertions(+), 7 deletions(-)
>>
>
> [...]
>
>> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
>> index bb458bf..e86d7f4 100644
>> --- a/arch/arm64/include/asm/kvm_mmu.h
>> +++ b/arch/arm64/include/asm/kvm_mmu.h
>> @@ -136,9 +136,10 @@ static inline unsigned long __kern_hyp_va(unsigned long v)
>> */
>> #define KVM_PHYS_SHIFT (40)
>>
>> -#define kvm_phys_shift(kvm) KVM_PHYS_SHIFT
>> +#define kvm_phys_shift(kvm) (kvm->arch.phys_shift)
>> #define kvm_phys_size(kvm) (_AC(1, ULL) << kvm_phys_shift(kvm))
>> #define kvm_phys_mask(kvm) (kvm_phys_size(kvm) - _AC(1, ULL))
>> +#define kvm_stage2_levels(kvm) (kvm->arch.s2_levels)
>>
>> static inline bool kvm_page_empty(void *ptr)
>> {
>
> [...]
>
>> diff --git a/arch/arm64/include/asm/stage2_pgtable.h b/arch/arm64/include/asm/stage2_pgtable.h
>> index 33e8ebb..9b75b83 100644
>> --- a/arch/arm64/include/asm/stage2_pgtable.h
>> +++ b/arch/arm64/include/asm/stage2_pgtable.h
>> @@ -44,7 +44,6 @@
>> */
>> #define __s2_pgd_ptrs(pa, lvls) (1 << ((pa) - pt_levels_pgdir_shift((lvls))))
>>
>> -#define kvm_stage2_levels(kvm) stage2_pt_levels(kvm_phys_shift(kvm))
>> #define stage2_pgdir_shift(kvm) \
>> pt_levels_pgdir_shift(kvm_stage2_levels(kvm))
>> #define stage2_pgdir_size(kvm) (_AC(1, UL) << stage2_pgdir_shift((kvm)))
>
> [...]
>
>> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
>> index 7a264c6..746f38e 100644
>> --- a/virt/kvm/arm/mmu.c
>> +++ b/virt/kvm/arm/mmu.c
>> @@ -753,6 +753,10 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm)
>> return -EINVAL;
>> }
>>
>> + /* Make sure we have the stage2 configured for this VM */
>> + if (WARN_ON(!kvm_stage2_levels(kvm)))
>> + return -EINVAL;
>> +
>
> This hunk breaks the 32-bit build as kvm_stag2_levels() isn't defined on
> arm.

Thanks for spotting. I have fixed this locally in my next version to check
for the kvm_phys_shift(), as I plan to delay the levels selection to the
actual allocation of the table, giving us a fall back to increase the level
if we are unable to allocate contiguous pages (e.g, 16 * 64K pages with say 46bit
IPA).


Cheers
Suzuki

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