vma_lookup() finds the vma of a specific address with a cleaner interface
and is more readable.

Link: https://lkml.kernel.org/r/20210521174745.2219620-5-Liam.Howlett@Oracle.comSigned-off-by: NLiam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: NLaurent Dufour <ldufour@linux.ibm.com>
Acked-by: NDavid Hildenbrand <david@redhat.com>
Acked-by: NDavidlohr Bueso <dbueso@suse.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/arm64/kvm/mmu.c:1114:9-10: WARNING: return of 0/1 in function 'kvm_age_gfn' with return type bool
arch/arm64/kvm/mmu.c:1084:9-10: WARNING: return of 0/1 in function 'kvm_set_spte_gfn' with return type bool
arch/arm64/kvm/mmu.c:1127:9-10: WARNING: return of 0/1 in function 'kvm_test_age_gfn' with return type bool
arch/arm64/kvm/mmu.c:1070:9-10: WARNING: return of 0/1 in function 'kvm_unmap_gfn_range' with return type bool

 Return statements in functions returning bool should use
 true/false instead of 1/0.
Generated by: scripts/coccinelle/misc/boolreturn.cocci

Fixes: cd4c7183 ("KVM: arm64: Convert to the gfn-based MMU notifier callbacks")
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: Nkernel test robot <lkp@intel.com>
Reviewed-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210426223357.GA45871@cd4295a34ed8

Move arm64 to the gfn-base MMU notifier APIs, which do the hva->gfn
lookup in common code.

No meaningful functional change intended, though the exact order of
operations is slightly different since the memslot lookups occur before
calling into arch code.
Reviewed-by: NMarc Zyngier <maz@kernel.org>
Tested-by: NMarc Zyngier <maz@kernel.org>
Signed-off-by: NSean Christopherson <seanjc@google.com>
Message-Id: <20210402005658.3024832-4-seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Move arm64's MMU notifier trace events into common code in preparation
for doing the hva->gfn lookup in common code.  The alternative would be
to trace the gfn instead of hva, but that's not obviously better and
could also be done in common code.  Tracing the notifiers is also quite
handy for debug regardless of architecture.

Remove a completely redundant tracepoint from PPC e500.
Signed-off-by: NSean Christopherson <seanjc@google.com>
Message-Id: <20210326021957.1424875-10-seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We needn't retrieve the memory slot again in user_mem_abort() because
the corresponding memory slot has been passed from the caller. This
would save some CPU cycles. For example, the time used to write 1GB
memory, which is backed by 2MB hugetlb pages and write-protected, is
dropped by 6.8% from 928ms to 864ms.
Signed-off-by: NGavin Shan <gshan@redhat.com>
Reviewed-by: NKeqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210316041126.81860-4-gshan@redhat.com

find_vma_intersection() has been existing to search the intersected
vma. This uses the function where it's applicable, to simplify the
code.
Signed-off-by: NGavin Shan <gshan@redhat.com>
Reviewed-by: NKeqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210316041126.81860-3-gshan@redhat.com

We needn't expose the function as it's only used by mmu.c since it
was introduced by commit c6473555 ("KVM: arm: Add initial dirty
page locking support").
Signed-off-by: NGavin Shan <gshan@redhat.com>
Reviewed-by: NKeqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210316041126.81860-2-gshan@redhat.com

In order to make use of the stage 2 pgtable code for the host stage 2,
change kvm_s2_mmu to use a kvm_arch pointer in lieu of the kvm pointer,
as the host will have the former but not the latter.
Acked-by: NWill Deacon <will@kernel.org>
Signed-off-by: NQuentin Perret <qperret@google.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-21-qperret@google.com

In order to make use of the stage 2 pgtable code for the host stage 2,
use struct kvm_arch in lieu of struct kvm as the host will have the
former but not the latter.
Acked-by: NWill Deacon <will@kernel.org>
Signed-off-by: NQuentin Perret <qperret@google.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-20-qperret@google.com

Previous commits have introduced infrastructure to enable the EL2 code
to manage its own stage 1 mappings. However, this was preliminary work,
and none of it is currently in use.

Put all of this together by elevating the mapping creation at EL2 when
memory protection is enabled. In this case, the host kernel running
at EL1 still creates _temporary_ EL2 mappings, only used while
initializing the hypervisor, but frees them right after.

As such, all calls to create_hyp_mappings() after kvm init has finished
turn into hypercalls, as the host now has no 'legal' way to modify the
hypevisor page tables directly.
Acked-by: NWill Deacon <will@kernel.org>
Signed-off-by: NQuentin Perret <qperret@google.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-19-qperret@google.com

In preparation for enabling the creation of page-tables at EL2, factor
all memory allocation out of the page-table code, hence making it
re-usable with any compatible memory allocator.

No functional changes intended.
Acked-by: NWill Deacon <will@kernel.org>
Signed-off-by: NQuentin Perret <qperret@google.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-7-qperret@google.com

When registering a memslot, we check the size and location of that
memslot against the IPA size to ensure that we can provide guest
access to the whole of the memory.

Unfortunately, this check rejects memslot that end-up at the exact
limit of the addressing capability for a given IPA size. For example,
it refuses the creation of a 2GB memslot at 0x8000000 with a 32bit
IPA space.

Fix it by relaxing the check to accept a memslot reaching the
limit of the IPA space.

Fixes: c3058d5d ("arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE")
Reviewed-by: NEric Auger <eric.auger@redhat.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Reviewed-by: NAndrew Jones <drjones@redhat.com>
Link: https://lore.kernel.org/r/20210311100016.3830038-3-maz@kernel.org

We now set the pfn dirty and mark the page dirty before calling fault
handlers in user_mem_abort(), so we might end up having spurious dirty
pages if update of permissions or mapping has failed. Let's move these
two operations after the fault handlers, and they will be done only if
the fault has been handled successfully.

When an -EAGAIN errno is returned from the map handler, we hope to the
vcpu to enter guest directly instead of exiting back to userspace, so
adjust the return value at the end of function.
Signed-off-by: NYanan Wang <wangyanan55@huawei.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210114121350.123684-4-wangyanan55@huawei.com

If we get a FSC_PERM fault, just using (logging_active && writable) to
determine calling kvm_pgtable_stage2_map(). There will be two more cases
we should consider.

(1) After logging_active is configged back to false from true. When we
get a FSC_PERM fault with write_fault and adjustment of hugepage is needed,
we should merge tables back to a block entry. This case is ignored by still
calling kvm_pgtable_stage2_relax_perms(), which will lead to an endless
loop and guest panic due to soft lockup.

(2) We use (FSC_PERM && logging_active && writable) to determine
collapsing a block entry into a table by calling kvm_pgtable_stage2_map().
But sometimes we may only need to relax permissions when trying to write
to a page other than a block.
In this condition,using kvm_pgtable_stage2_relax_perms() will be fine.

The ISS filed bit[1:0] in ESR_EL2 regesiter indicates the stage2 lookup
level at which a D-abort or I-abort occurred. By comparing granule of
the fault lookup level with vma_pagesize, we can strictly distinguish
conditions of calling kvm_pgtable_stage2_relax_perms() or
kvm_pgtable_stage2_map(), and the above two cases will be well considered.
Suggested-by: NKeqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: NYanan Wang <wangyanan55@huawei.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Acked-by: NWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201201201034.116760-4-wangyanan55@huawei.com

In an effort to remove the vcpu PC manipulations from EL1 on nVHE
systems, move kvm_skip_instr() to be HYP-specific. EL1's intent
to increment PC post emulation is now signalled via a flag in the
vcpu structure.
Signed-off-by: NMarc Zyngier <maz@kernel.org>

There is no need to feed the result of kvm_vcpu_trap_il_is32bit()
to kvm_skip_instr(), as only AArch32 has a variable length ISA, and
this helper can equally be called from kvm_skip_instr32(), reducing
the complexity at all the call sites.
Acked-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>

The PUD and PMD are folded into PGD when the following options are
enabled. In that case, PUD_SHIFT is equal to PMD_SHIFT and we fail
to build with the indicated errors:

   CONFIG_ARM64_VA_BITS_42=y
   CONFIG_ARM64_PAGE_SHIFT=16
   CONFIG_PGTABLE_LEVELS=3

   arch/arm64/kvm/mmu.c: In function ‘user_mem_abort’:
   arch/arm64/kvm/mmu.c:798:2: error: duplicate case value
     case PMD_SHIFT:
     ^~~~
   arch/arm64/kvm/mmu.c:791:2: note: previously used here
     case PUD_SHIFT:
     ^~~~

This fixes the issue by skipping the check on PUD huge page when PUD
and PMD are folded into PGD.

Fixes: 2f40c460 ("KVM: arm64: Use fallback mapping sizes for contiguous huge page sizes")
Reported-by: NEric Auger <eric.auger@redhat.com>
Signed-off-by: NGavin Shan <gshan@redhat.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201103003009.32955-1-gshan@redhat.com

VFIO allows a device driver to resolve a fault by mapping a MMIO
range. This can be subsequently result in user_mem_abort() to
try and compute a huge mapping based on the MMIO pfn, which is
a sure recipe for things to go wrong.

Instead, force a PTE mapping when the pfn faulted in has a device
mapping.

Fixes: 6d674e28 ("KVM: arm/arm64: Properly handle faulting of device mappings")
Suggested-by: NMarc Zyngier <maz@kernel.org>
Signed-off-by: NSantosh Shukla <sashukla@nvidia.com>
[maz: rewritten commit message]
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/1603711447-11998-2-git-send-email-sashukla@nvidia.com

Although huge pages can be created out of multiple contiguous PMDs
or PTEs, the corresponding sizes are not supported at Stage-2 yet.

Instead of failing the mapping, fall back to the nearer supported
mapping size (CONT_PMD to PMD and CONT_PTE to PTE respectively).
Suggested-by: NMarc Zyngier <maz@kernel.org>
Signed-off-by: NGavin Shan <gshan@redhat.com>
[maz: rewritten commit message]
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201025230626.18501-1-gshan@redhat.com

If a change in the MMU notifier sequence number forces user_mem_abort()
to return early when attempting to handle a stage-2 fault, we return
uninitialised stack to kvm_handle_guest_abort(), which could potentially
result in the injection of an external abort into the guest or a spurious
return to userspace. Neither or these are what we want to do.

Initialise 'ret' to 0 in user_mem_abort() so that bailing due to a
change in the MMU notrifier sequence number is treated as though the
fault was handled.
Reported-by: Nkernel test robot <lkp@intel.com>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NAlexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Gavin Shan <gshan@redhat.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20200930102442.16142-1-will@kernel.org

KVM currently assumes that an instruction abort can never be a write.
This is in general true, except when the abort is triggered by
a S1PTW on instruction fetch that tries to update the S1 page tables
(to set AF, for example).

This can happen if the page tables have been paged out and brought
back in without seeing a direct write to them (they are thus marked
read only), and the fault handling code will make the PT executable(!)
instead of writable. The guest gets stuck forever.

In these conditions, the permission fault must be considered as
a write so that the Stage-1 update can take place. This is essentially
the I-side equivalent of the problem fixed by 60e21a0e ("arm64: KVM:
Take S1 walks into account when determining S2 write faults").

Update kvm_is_write_fault() to return true on IABT+S1PTW, and introduce
kvm_vcpu_trap_is_exec_fault() that only return true when no faulting
on a S1 fault. Additionally, kvm_vcpu_dabt_iss1tw() is renamed to
kvm_vcpu_abt_iss1tw(), as the above makes it plain that it isn't
specific to data abort.
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NWill Deacon <will@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200915104218.1284701-2-maz@kernel.org

Fix following warnings caused by mismatch bewteen function parameters
and comments.
arch/arm64/kvm/mmu.c:128: warning: Function parameter or member 'mmu' not described in '__unmap_stage2_range'
arch/arm64/kvm/mmu.c:128: warning: Function parameter or member 'may_block' not described in '__unmap_stage2_range'
arch/arm64/kvm/mmu.c:128: warning: Excess function parameter 'kvm' description in '__unmap_stage2_range'
arch/arm64/kvm/mmu.c:499: warning: Function parameter or member 'writable' not described in 'kvm_phys_addr_ioremap'
arch/arm64/kvm/mmu.c:538: warning: Function parameter or member 'mmu' not described in 'stage2_wp_range'
arch/arm64/kvm/mmu.c:538: warning: Excess function parameter 'kvm' description in 'stage2_wp_range'
Signed-off-by: NXiaofei Tan <tanxiaofei@huawei.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Acked-by: NWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/1600307269-50957-1-git-send-email-tanxiaofei@huawei.com

As a result of a KVM_SET_USER_MEMORY_REGION ioctl, KVM flushes the
dcache for the memslot being changed to ensure a consistent view of memory
between the host and the guest: the host runs with caches enabled, and
it is possible for the data written by the hypervisor to still be in the
caches, but the guest is running with stage 1 disabled, meaning data
accesses are to Device-nGnRnE memory, bypassing the caches entirely.

Flushing the dcache is not necessary when KVM enables FWB, because it
forces the guest to uses cacheable memory accesses.

The current behaviour does not change, as the dcache flush helpers execute
the cache operation only if FWB is not enabled, but walking the stage 2
table is avoided.
Signed-off-by: NAlexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200915170442.131635-1-alexandru.elisei@arm.com

When userspace uses hugetlbfs for the VM memory, user_mem_abort() tries to
use the same block size to map the faulting IPA in stage 2. If stage 2
cannot the same block mapping because the block size doesn't fit in the
memslot or the memslot is not properly aligned, user_mem_abort() will fall
back to a page mapping, regardless of the block size. We can do better for
PUD backed hugetlbfs by checking if a PMD block mapping is supported before
deciding to use a page.

vma_pagesize is an unsigned long, use 1UL instead of 1ULL when assigning
its value.
Signed-off-by: NAlexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200910133351.118191-1-alexandru.elisei@arm.com

The stage-2 page-tables are entirely encapsulated by the 'pgt' field of
'struct kvm_s2_mmu', so remove the unused 'pgd' field.
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-21-will@kernel.org

Now that KVM is using the generic page-table code to manage the guest
stage-2 page-tables, we can remove a bunch of unused macros, #defines
and static inline functions from the old implementation.
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-20-will@kernel.org

In preparation for removing the 'pgd' field of 'struct kvm_s2_mmu',
update the few remaining users to check the 'pgt' field instead.
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-19-will@kernel.org

Convert user_mem_abort() to call kvm_pgtable_stage2_relax_perms() when
handling a stage-2 permission fault and kvm_pgtable_stage2_map() when
handling a stage-2 translation fault, rather than walking the page-table
manually.
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Reviewed-by: NAlexandru Elisei <alexandru.elisei@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-18-will@kernel.org

Convert stage2_flush_memslot() to call the kvm_pgtable_stage2_flush()
function of the generic page-table code instead of walking the page-table
directly.
Signed-off-by: NQuentin Perret <qperret@google.com>
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200911132529.19844-16-will@kernel.org

Convert stage2_wp_range() to call the kvm_pgtable_stage2_wrprotect()
function of the generic page-table code instead of walking the page-table
directly.
Signed-off-by: NQuentin Perret <qperret@google.com>
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200911132529.19844-14-will@kernel.org

Convert the page-aging functions and access fault handler to use the
generic page-table code instead of walking the page-table directly.
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Reviewed-by: NAlexandru Elisei <alexandru.elisei@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-12-will@kernel.org

Convert unmap_stage2_range() to use kvm_pgtable_stage2_unmap() instead
of walking the page-table directly.
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-10-will@kernel.org

Convert kvm_set_spte_hva() to use kvm_pgtable_stage2_map() instead
of stage2_set_pte().
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-9-will@kernel.org

Convert kvm_phys_addr_ioremap() to use kvm_pgtable_stage2_map() instead
of stage2_set_pte().
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-8-will@kernel.org

Introduce alloc() and free() functions to the generic page-table code
for guest stage-2 page-tables and plumb these into the existing KVM
page-table allocator. Subsequent patches will convert other operations
within the KVM allocator over to the generic code.
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-6-will@kernel.org

Now that we have a shiny new page-table allocator, replace the hyp
page-table code with calls into the new API. This also allows us to
remove the extended idmap code, as we can now simply ensure that the
VA size is large enough to map everything we need.
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-5-will@kernel.org

kvm_mmu_free_memory_caches() is only called by kvm_arch_vcpu_destroy(),
so inline the implementation and get rid of the extra function.
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-2-will@kernel.org

Commit 196f878a (" KVM: arm/arm64: Signal SIGBUS when stage2 discovers
hwpoison memory") modifies user_mem_abort() to send a SIGBUS signal when
the fault IPA maps to a hwpoisoned page. Commit 1559b758 ("KVM:
arm/arm64: Re-check VMA on detecting a poisoned page") changed
kvm_send_hwpoison_signal() to use the page shift instead of the VMA because
at that point the code had already released the mmap lock, which means
userspace could have modified the VMA.

If userspace uses hugetlbfs for the VM memory, user_mem_abort() tries to
map the guest fault IPA using block mappings in stage 2. That is not always
possible, if, for example, userspace uses dirty page logging for the VM.
Update the page shift appropriately in those cases when we downgrade the
stage 2 entry from a block mapping to a page.

Fixes: 1559b758 ("KVM: arm/arm64: Re-check VMA on detecting a poisoned page")
Signed-off-by: NAlexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Link: https://lore.kernel.org/r/20200901133357.52640-2-alexandru.elisei@arm.com

For the obscure cases where PMD and PUD are the same size
(64kB pages with 42bit VA, for example, which results in only
two levels of page tables), we can't map anything as a PUD,
because there is... erm... no PUD to speak of. Everything is
either a PMD or a PTE.

So let's only try and map a PUD when its size is different from
that of a PMD.

Cc: stable@vger.kernel.org
Fixes: b8e0ba7c ("KVM: arm64: Add support for creating PUD hugepages at stage 2")
Reported-by: NGavin Shan <gshan@redhat.com>
Reported-by: NEric Auger <eric.auger@redhat.com>
Reviewed-by: NAlexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: NGavin Shan <gshan@redhat.com>
Tested-by: NGavin Shan <gshan@redhat.com>
Tested-by: NEric Auger <eric.auger@redhat.com>
Tested-by: NAlexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>

When an MMU notifier call results in unmapping a range that spans multiple
PGDs, we end up calling into cond_resched_lock() when crossing a PGD boundary,
since this avoids running into RCU stalls during VM teardown. Unfortunately,
if the VM is destroyed as a result of OOM, then blocking is not permitted
and the call to the scheduler triggers the following BUG():

 | BUG: sleeping function called from invalid context at arch/arm64/kvm/mmu.c:394
 | in_atomic(): 1, irqs_disabled(): 0, non_block: 1, pid: 36, name: oom_reaper
 | INFO: lockdep is turned off.
 | CPU: 3 PID: 36 Comm: oom_reaper Not tainted 5.8.0 #1
 | Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
 | Call trace:
 |  dump_backtrace+0x0/0x284
 |  show_stack+0x1c/0x28
 |  dump_stack+0xf0/0x1a4
 |  ___might_sleep+0x2bc/0x2cc
 |  unmap_stage2_range+0x160/0x1ac
 |  kvm_unmap_hva_range+0x1a0/0x1c8
 |  kvm_mmu_notifier_invalidate_range_start+0x8c/0xf8
 |  __mmu_notifier_invalidate_range_start+0x218/0x31c
 |  mmu_notifier_invalidate_range_start_nonblock+0x78/0xb0
 |  __oom_reap_task_mm+0x128/0x268
 |  oom_reap_task+0xac/0x298
 |  oom_reaper+0x178/0x17c
 |  kthread+0x1e4/0x1fc
 |  ret_from_fork+0x10/0x30

Use the new 'flags' argument to kvm_unmap_hva_range() to ensure that we
only reschedule if MMU_NOTIFIER_RANGE_BLOCKABLE is set in the notifier
flags.

Cc: <stable@vger.kernel.org>
Fixes: 8b3405e3 ("kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd")
Cc: Marc Zyngier <maz@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: NWill Deacon <will@kernel.org>
Message-Id: <20200811102725.7121-3-will@kernel.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>