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ANDROID: KVM: arm64: iommu: Snapshot host stage-2 at driver init

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IOMMU drivers may need to keep their own state of the host stage-2
mappings, eg. because they cannot share the PTs with the CPU. To this
end, walk the host stage-2 at driver init time and pass the current
state of host stage-2 mappings to the driver.

The driver initialization lock is released together with host_kvm
lock. That was the driver starts receiving stage-2 updates immediately
after the snapshot is taken.

Bug: 190463801
Change-Id: I5a5b0e064c5c88e210e28e343314318a2a1bffda
Signed-off-by: David Brazdil <dbrazdil@google.com>
(cherry picked from commit 1ec4b346d0)
Signed-off-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
This commit is contained in:
David Brazdil
2022-02-14 23:34:26 +00:00
committed by Quentin Perret
parent d9bab2b5ed
commit f78c4e5b3f
1 changed files with 46 additions and 1 deletions
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47
arch/arm64/kvm/hyp/nvhe/iommu.c
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@@ -149,6 +149,40 @@ static bool is_mmio_range(phys_addr_t base, size_t size)
return true;
}
static int __snapshot_host_stage2(u64 start, u64 end, u32 level,
kvm_pte_t *ptep,
enum kvm_pgtable_walk_flags flags,
void * const arg)
{
struct pkvm_iommu_driver * const drv = arg;
enum kvm_pgtable_prot prot;
kvm_pte_t pte = *ptep;
/*
* Valid stage-2 entries are created lazily, invalid ones eagerly.
* Note: In the future we may need to check if [start,end) is MMIO.
*/
prot = (!pte || kvm_pte_valid(pte)) ? PKVM_HOST_MEM_PROT : 0;
drv->ops->host_stage2_idmap_prepare(start, end, prot);
return 0;
}
static int snapshot_host_stage2(struct pkvm_iommu_driver * const drv)
{
struct kvm_pgtable_walker walker = {
.cb = __snapshot_host_stage2,
.arg = drv,
.flags = KVM_PGTABLE_WALK_LEAF,
};
struct kvm_pgtable *pgt = &host_mmu.pgt;
if (!drv->ops->host_stage2_idmap_prepare)
return 0;
return kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker);
}
static bool validate_against_existing_iommus(struct pkvm_iommu *dev)
{
struct pkvm_iommu *other;
@@ -216,8 +250,19 @@ int __pkvm_iommu_driver_init(enum pkvm_iommu_driver_id id, void *data, size_t si
goto out;
}
/*
* Walk host stage-2 and pass current mappings to the driver. Start
* accepting host stage-2 updates as soon as the host lock is released.
*/
host_lock_component();
ret = snapshot_host_stage2(drv);
if (!ret)
driver_release_init(drv, /*success=*/true);
host_unlock_component();
out:
driver_release_init(drv, /*success=*/!ret);
if (ret)
driver_release_init(drv, /*success=*/false);
return ret;
}