[PATCH 3/6] arm/arm64: KVM: add 'writable' parameter to kvm_phys_addr_ioremap

[Ard Biesheuvel]

On 9 October 2014 15:07, Marc Zyngier <marc.zyngier at arm.com> wrote:
> On 17/09/14 22:56, Ard Biesheuvel wrote:
>> Add support for read-only MMIO passthrough mappings by adding a
>> 'writable' parameter to kvm_phys_addr_ioremap. For the moment,
>> mappings will be read-write even if 'writable' is false, but once
>> the definition of PAGE_S2_DEVICE gets changed, those mappings will
>> be created read-only.
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
>> ---
>>  arch/arm/kvm/mmu.c               | 5 ++++-
>>  arch/arm64/include/asm/kvm_mmu.h | 2 +-
>>  virt/kvm/arm/vgic.c              | 3 ++-
>>  3 files changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
>> index c093e95ff7ef..fe53c3a30383 100644
>> --- a/arch/arm/kvm/mmu.c
>> +++ b/arch/arm/kvm/mmu.c
>> @@ -674,7 +674,7 @@ static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
>>   * @size:    The size of the mapping
>>   */
>>  int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
>> -                       phys_addr_t pa, unsigned long size)
>> +                       phys_addr_t pa, unsigned long size, bool writable)
>>  {
>>       phys_addr_t addr, end;
>>       int ret = 0;
>> @@ -687,6 +687,9 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
>>       for (addr = guest_ipa; addr < end; addr += PAGE_SIZE) {
>>               pte_t pte = pfn_pte(pfn, PAGE_S2_DEVICE);
>>
>> +             if (writable)
>> +                     kvm_set_s2pte_writable(&pte);
>> +
>>               ret = mmu_topup_memory_cache(&cache, 2, 2);
>>               if (ret)
>>                       goto out;
>> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
>> index 737da742b293..7474e611bb2a 100644
>> --- a/arch/arm64/include/asm/kvm_mmu.h
>> +++ b/arch/arm64/include/asm/kvm_mmu.h
>> @@ -78,7 +78,7 @@ void free_hyp_pgds(void);
>>  int kvm_alloc_stage2_pgd(struct kvm *kvm);
>>  void kvm_free_stage2_pgd(struct kvm *kvm);
>>  int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
>> -                       phys_addr_t pa, unsigned long size);
>> +                       phys_addr_t pa, unsigned long size, bool writable);
>
> I'm afraid you missed the equivalent 32bit declaration.
>

Christoffer had spotted that as well, and indicated he would not mind
fixing it up when applying.

>>
>>  int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run);
>>
>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>> index 73eba793b17f..c2bdbf4e25c2 100644
>> --- a/virt/kvm/arm/vgic.c
>> +++ b/virt/kvm/arm/vgic.c
>> @@ -1628,7 +1628,8 @@ int kvm_vgic_init(struct kvm *kvm)
>>       }
>>
>>       ret = kvm_phys_addr_ioremap(kvm, kvm->arch.vgic.vgic_cpu_base,
>> -                                 vgic->vcpu_base, KVM_VGIC_V2_CPU_SIZE);
>> +                                 vgic->vcpu_base, KVM_VGIC_V2_CPU_SIZE,
>> +                                 true);
>>       if (ret) {
>>               kvm_err("Unable to remap VGIC CPU to VCPU\n");
>>               goto out;
>>
>
> Thanks,
>
>         M.
> --
> Jazz is not dead. It just smells funny...
>