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ANDROID: KVM: arm64: pkvm: Add MMIO guard infrastructure

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Introduce the infrastructure required to identify an IPA region
that is expected to be used as an MMIO window.

This include mapping, unmapping and checking the regions. Nothing
calls into it yet, so no expected functional change.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Bug: 209580772
Change-Id: I227eaa28b98e067e3daae4f9e1071eb37a6761cc
Signed-off-by: Will Deacon <willdeacon@google.com>
This commit is contained in:
Marc Zyngier
2022-01-06 10:29:13 +00:00
committed by Will Deacon
parent 4bd3bae3cc
commit f01af370af
2 changed files with 108 additions and 0 deletions
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3
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
View File

@@ -68,6 +68,9 @@ int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct kvm_vcpu *vcpu);
int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct kvm_vcpu *vcpu);
int __pkvm_guest_share_host(struct kvm_vcpu *vcpu, u64 ipa);
int __pkvm_guest_unshare_host(struct kvm_vcpu *vcpu, u64 ipa);
int __pkvm_install_ioguard_page(struct kvm_vcpu *vcpu, u64 ipa);
int __pkvm_remove_ioguard_page(struct kvm_vcpu *vcpu, u64 ipa);
bool __pkvm_check_ioguard_page(struct kvm_vcpu *vcpu);
bool addr_is_memory(phys_addr_t phys);
int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot);

105
arch/arm64/kvm/hyp/nvhe/mem_protect.c
View File

@@ -1819,3 +1819,108 @@ unlock:
return ret;
}
/* Replace this with something more structured once day */
#define MMIO_NOTE (('M' << 24 | 'M' << 16 | 'I' << 8 | 'O') << 1)
static bool __check_ioguard_page(struct kvm_vcpu *vcpu, u64 ipa)
{
struct kvm_shadow_vm *vm = vcpu->arch.pkvm.shadow_vm;
kvm_pte_t pte;
u32 level;
int ret;
ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level);
if (ret)
return false;
/* Must be a PAGE_SIZE mapping with our annotation */
return (BIT(ARM64_HW_PGTABLE_LEVEL_SHIFT(level)) == PAGE_SIZE &&
pte == MMIO_NOTE);
}
int __pkvm_install_ioguard_page(struct kvm_vcpu *vcpu, u64 ipa)
{
struct kvm_shadow_vm *vm;
kvm_pte_t pte;
u32 level;
int ret;
vm = vcpu->arch.pkvm.shadow_vm;
if (!test_bit(KVM_ARCH_FLAG_MMIO_GUARD, &vm->arch.flags))
return -EINVAL;
if (ipa & ~PAGE_MASK)
return -EINVAL;
guest_lock_component(vcpu);
ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level);
if (ret)
goto unlock;
if (pte && BIT(ARM64_HW_PGTABLE_LEVEL_SHIFT(level)) == PAGE_SIZE) {
/*
* Already flagged as MMIO, let's accept it, and fail
* otherwise
*/
if (pte != MMIO_NOTE)
ret = -EBUSY;
goto unlock;
}
ret = kvm_pgtable_stage2_annotate(&vm->pgt, ipa, PAGE_SIZE,
&vcpu->arch.pkvm_memcache,
MMIO_NOTE);
unlock:
guest_unlock_component(vcpu);
return ret;
}
int __pkvm_remove_ioguard_page(struct kvm_vcpu *vcpu, u64 ipa)
{
struct kvm_shadow_vm *vm = vcpu->arch.pkvm.shadow_vm;
if (!test_bit(KVM_ARCH_FLAG_MMIO_GUARD, &vm->arch.flags))
return -EINVAL;
guest_lock_component(vcpu);
if (__check_ioguard_page(vcpu, ipa)) {
struct kvm_shadow_vm *vm = vcpu->arch.pkvm.shadow_vm;
kvm_pgtable_stage2_unmap(&vm->pgt,
ALIGN_DOWN(ipa, PAGE_SIZE), PAGE_SIZE);
}
guest_unlock_component(vcpu);
return 0;
}
bool __pkvm_check_ioguard_page(struct kvm_vcpu *vcpu)
{
struct kvm_shadow_vm *vm = vcpu->arch.pkvm.shadow_vm;
u64 ipa, end;
bool ret;
if (!kvm_vcpu_dabt_isvalid(vcpu))
return false;
if (!test_bit(KVM_ARCH_FLAG_MMIO_GUARD, &vm->arch.flags))
return true;
ipa = kvm_vcpu_get_fault_ipa(vcpu);
ipa |= kvm_vcpu_get_hfar(vcpu) & FAR_MASK;
end = ipa + kvm_vcpu_dabt_get_as(vcpu) - 1;
guest_lock_component(vcpu);
ret = __check_ioguard_page(vcpu, ipa);
if ((end & PAGE_MASK) != (ipa & PAGE_MASK))
ret &= __check_ioguard_page(vcpu, end);
guest_unlock_component(vcpu);
return ret;
}