Commit:
b8865767 ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping

introduced some code in user_mem_abort that failed to compile if
STRICT_MM_TYPECHECKS was enabled.

This patch fixes up the failing comparison.
Signed-off-by: NSteve Capper <steve.capper@linaro.org>
Reviewed-by: NKim Phillips <kim.phillips@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

When creating or moving a memslot, make sure the IPA space is within the
addressable range of the guest.  Otherwise, user space can create too
large a memslot and KVM would try to access potentially unallocated page
table entries when inserting entries in the Stage-2 page tables.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

This patch adds the necessary support for all host kernel PGSIZE and
VA_SPACE configuration options for both EL2 and the Stage-2 page tables.

However, for 40bit and 42bit PARange systems, the architecture mandates
that VTCR_EL2.SL0 is maximum 1, resulting in fewer levels of stage-2
pagge tables than levels of host kernel page tables.  At the same time,
systems with a PARange > 42bit, we limit the IPA range by always setting
VTCR_EL2.T0SZ to 24.

To solve the situation with different levels of page tables for Stage-2
translation than the host kernel page tables, we allocate a dummy PGD
with pointers to our actual inital level Stage-2 page table, in order
for us to reuse the kernel pgtable manipulation primitives.  Reproducing
all these in KVM does not look pretty and unnecessarily complicates the
32-bit side.

Systems with a PARange < 40bits are not yet supported.

 [ I have reworked this patch from its original form submitted by
   Jungseok to take the architecture constraints into consideration.
   There were too many changes from the original patch for me to
   preserve the authorship.  Thanks to Catalin Marinas for his help in
   figuring out a good solution to this challenge.  I have also fixed
   various bugs and missing error code handling from the original
   patch. - Christoffer ]
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NJungseok Lee <jungseoklee85@gmail.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

There is really no point in faulting in memory regions page by page
if they are not backed by demand paged system RAM but by a linear
passthrough mapping of a host MMIO region. So instead, detect such
regions at setup time and install the mappings for the backing all
at once.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

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.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Handle the potential NULL return value of find_vma_intersection()
before dereferencing it.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Pass __GFP_ZERO to __get_free_pages() instead of calling memset()
explicitly.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

When we catch something that's not a permission fault or a translation
fault, we log the unsupported FSC in the kernel log, but we were masking
off the bottom bits of the FSC which was not very helpful.

Also correctly report the FSC for data and instruction faults rather
than telling people it was a DFCS, which doesn't exist in the ARM ARM.
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

The ISS encoding for an exception from a Data Abort has a WnR
bit[6] that indicates whether the Data Abort was caused by a
read or a write instruction. While there are several fields
in the encoding that are only valid if the ISV bit[24] is set,
WnR is not one of them, so we can read it unconditionally.

Instead of fixing both implementations of kvm_is_write_fault()
in place, reimplement it just once using kvm_vcpu_dabt_iswrite(),
which already does the right thing with respect to the WnR bit.
Also fix up the callers to pass 'vcpu'
Acked-by: NLaszlo Ersek <lersek@redhat.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

When userspace loads code and data in a read-only memory regions, KVM
needs to be able to handle this on arm and arm64.  Specifically this is
used when running code directly from a read-only flash device; the
common scenario is a UEFI blob loaded with the -bios option in QEMU.

Note that the MMIO exit on writes to a read-only memory is ABI and can
be used to emulate block-erase style flash devices.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

A userspace process can map device MMIO memory via VFIO or /dev/mem,
e.g., for platform device passthrough support in QEMU.

During early development, we found the PAGE_S2 memory type being used
for MMIO mappings.  This patch corrects that by using the more strongly
ordered memory type for device MMIO mappings: PAGE_S2_DEVICE.
Signed-off-by: NKim Phillips <kim.phillips@linaro.org>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

Currently when a KVM region is deleted or moved after
KVM_SET_USER_MEMORY_REGION ioctl, the corresponding
intermediate physical memory is not unmapped.

This patch corrects this and unmaps the region's IPA range
in kvm_arch_commit_memory_region using unmap_stage2_range.
Signed-off-by: NEric Auger <eric.auger@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

unmap_range() was utterly broken, to quote Marc, and broke in all sorts
of situations.  It was also quite complicated to follow and didn't
follow the usual scheme of having a separate iterating function for each
level of page tables.

Address this by refactoring the code and introduce a pgd_clear()
function.
Reviewed-by: NJungseok Lee <jays.lee@samsung.com>
Reviewed-by: NMario Smarduch <m.smarduch@samsung.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

The kvm/mmu code shared by arm and arm64 uses kalloc() to allocate
a bounce page (if hypervisor init code crosses page boundary) and
hypervisor PGDs. The problem is that kalloc() does not guarantee
the proper alignment. In the case of the bounce page, the page sized
buffer allocated may also cross a page boundary negating the purpose
and leading to a hang during kvm initialization. Likewise the PGDs
allocated may not meet the minimum alignment requirements of the
underlying MMU. This patch uses __get_free_page() to guarantee the
worst case alignment needs of the bounce page and PGDs on both arm
and arm64.

Cc: <stable@vger.kernel.org> # 3.10+
Signed-off-by: NMark Salter <msalter@redhat.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Compiling with THP enabled leads to the following warning:

arch/arm/kvm/mmu.c: In function ‘unmap_range’:
arch/arm/kvm/mmu.c:177:39: warning: ‘pte’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   if (kvm_pmd_huge(*pmd) || page_empty(pte)) {
                                        ^
Code inspection reveals that these two cases are mutually exclusive,
so GCC is a bit overzealous here. Silence it anyway by initializing
pte to NULL and testing it later on.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>

When the guest runs with caches disabled (like in an early boot
sequence, for example), all the writes are diectly going to RAM,
bypassing the caches altogether.

Once the MMU and caches are enabled, whatever sits in the cache
becomes suddenly visible, which isn't what the guest expects.

A way to avoid this potential disaster is to invalidate the cache
when the MMU is being turned on. For this, we hook into the SCTLR_EL1
trapping code, and scan the stage-2 page tables, invalidating the
pages/sections that have already been mapped in.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>

The use of p*d_addr_end with stage-2 translation is slightly dodgy,
as the IPA is 40bits, while all the p*d_addr_end helpers are
taking an unsigned long (arm64 is fine with that as unligned long
is 64bit).

The fix is to introduce 64bit clean versions of the same helpers,
and use them in the stage-2 page table code.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>

In order for the guest with caches off to observe data written
contained in a given page, we need to make sure that page is
committed to memory, and not just hanging in the cache (as
guest accesses are completely bypassing the cache until it
decides to enable it).

For this purpose, hook into the coherent_icache_guest_page
function and flush the region if the guest SCTLR_EL1
register doesn't show the MMU  and caches as being enabled.
The function also get renamed to coherent_cache_guest_page.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>

The THP code in KVM/ARM is a bit restrictive in not allowing a THP
to be used if the VMA is not 2MB aligned. Actually, it is not so much
the VMA that matters, but the associated memslot:

A process can perfectly mmap a region with no particular alignment
restriction, and then pass a 2MB aligned address to KVM. In this
case, KVM will only use this 2MB aligned region, and will ignore
the range between vma->vm_start and memslot->userspace_addr.

It can also choose to place this memslot at whatever alignment it
wants in the IPA space. In the end, what matters is the relative
alignment of the user space and IPA mappings with respect to a
2M page. They absolutely must be the same if you want to use THP.

Cc: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

KVM initialisation fails on architectures implementing virt_to_idmap()
because virt_to_phys() on such architectures won't fetch you the correct
idmap page.

So update the KVM ARM code to use the virt_to_idmap() to fix the issue.
Since the KVM code is shared between arm and arm64, we create
kvm_virt_to_phys() and handle the redirection in respective headers.

Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Using virt_to_phys on percpu mappings is horribly wrong as it may be
backed by vmalloc.  Introduce kvm_kaddr_to_phys which translates both
types of valid kernel addresses to the corresponding physical address.

At the same time resolves a typing issue where we were storing the
physical address as a 32 bit unsigned long (on arm), truncating the
physical address for addresses above the 4GB limit.  This caused
breakage on Keystone.

Cc: <stable@vger.kernel.org>	[3.10+]
Reported-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Support transparent huge pages in KVM/ARM and KVM/ARM64.  The
transparent_hugepage_adjust is not very pretty, but this is also how
it's solved on x86 and seems to be simply an artifact on how THPs
behave.  This should eventually be shared across architectures if
possible, but that can always be changed down the road.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Support huge pages in KVM/ARM and KVM/ARM64.  The pud_huge checking on
the unmap path may feel a bit silly as the pud_huge check is always
defined to false, but the compiler should be smart about this.

Note: This deals only with VMAs marked as huge which are allocated by
users through hugetlbfs only.  Transparent huge pages can only be
detected by looking at the underlying pages (or the page tables
themselves) and this patch so far simply maps these on a page-by-page
level in the Stage-2 page tables.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

THe L_PTE_USER actually has nothing to do with stage 2 mappings and the
L_PTE_S2_RDWR value sets the readable bit, which was what L_PTE_USER
was used for before proper handling of stage 2 memory defines.

Changelog:
  [v3]: Drop call to kvm_set_s2pte_writable in mmu.c
  [v2]: Change default mappings to be r/w instead of r/o, as per Marc
     Zyngier's suggestion.

Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

When using 64kB pages, we only have two levels of page tables,
meaning that PGD, PUD and PMD are fused. In this case, trying
to refcount PUDs and PMDs independently is a a complete disaster,
as they are the same.

We manage to get it right for the allocation (stage2_set_pte uses
{pmd,pud}_none), but the unmapping path clears both pud and pmd
refcounts, which fails spectacularly with 2-level page tables.

The fix is to avoid calling clear_pud_entry when both the pmd and
pud pages are empty. For this, and instead of introducing another
pud_empty function, consolidate both pte_empty and pmd_empty into
page_empty (the code is actually identical) and use that to also
test the validity of the pud.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

The unmap_range function did not properly cover the case when the start
address was not aligned to PMD_SIZE or PUD_SIZE and an entire pte table
or pmd table was cleared, causing us to leak memory when incrementing
the addr.

The fix is to always move onto the next page table entry boundary
instead of adding the full size of the VA range covered by the
corresponding table level entry.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

S2_PGD_SIZE defines the number of pages used by a stage-2 PGD
and is unused, except for a VM_BUG_ON check that missuses the
define.

As the check is very unlikely to ever triggered except in
circumstances where KVM is the least of our worries, just kill
both the define and the VM_BUG_ON check.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@cs.columbia.edu>

The KVM/ARM MMU code doesn't take care of invalidating TLBs before
freeing a {pte,pmd} table. This could cause problems if the page
is reallocated and then speculated into by another CPU.
Reported-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NChristoffer Dall <cdall@cs.columbia.edu>

Now that we have the necessary infrastructure to boot a hotplugged CPU
at any point in time, wire a CPU notifier that will perform the HYP
init for the incoming CPU.

Note that this depends on the platform code and/or firmware to boot the
incoming CPU with HYP mode enabled and return to the kernel by following
the normal boot path (HYP stub installed).
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@cs.columbia.edu>

Our HYP init code suffers from two major design issues:
- it cannot support CPU hotplug, as we tear down the idmap very early
- it cannot perform a TLB invalidation when switching from init to
  runtime mappings, as pages are manipulated from PL1 exclusively

The hotplug problem mandates that we keep two sets of page tables
(boot and runtime). The TLB problem mandates that we're able to
transition from one PGD to another while in HYP, invalidating the TLBs
in the process.

To be able to do this, we need to share a page between the two page
tables. A page that will have the same VA in both configurations. All we
need is a VA that has the following properties:
- This VA can't be used to represent a kernel mapping.
- This VA will not conflict with the physical address of the kernel text

The vectors page seems to satisfy this requirement:
- The kernel never maps anything else there
- The kernel text being copied at the beginning of the physical memory,
  it is unlikely to use the last 64kB (I doubt we'll ever support KVM
  on a system with something like 4MB of RAM, but patches are very
  welcome).

Let's call this VA the trampoline VA.

Now, we map our init page at 3 locations:
- idmap in the boot pgd
- trampoline VA in the boot pgd
- trampoline VA in the runtime pgd

The init scenario is now the following:
- We jump in HYP with four parameters: boot HYP pgd, runtime HYP pgd,
  runtime stack, runtime vectors
- Enable the MMU with the boot pgd
- Jump to a target into the trampoline page (remember, this is the same
  physical page!)
- Now switch to the runtime pgd (same VA, and still the same physical
  page!)
- Invalidate TLBs
- Set stack and vectors
- Profit! (or eret, if you only care about the code).

Note that we keep the boot mapping permanently (it is not strictly an
idmap anymore) to allow for CPU hotplug in later patches.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@cs.columbia.edu>

There is no point in freeing HYP page tables differently from Stage-2.
They now have the same requirements, and should be dealt with the same way.

Promote unmap_stage2_range to be The One True Way, and get rid of a number
of nasty bugs in the process (good thing we never actually called free_hyp_pmds
before...).
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@cs.columbia.edu>

After the HYP page table rework, it is pretty easy to let the KVM
code provide its own idmap, rather than expecting the kernel to
provide it. It takes actually less code to do so.
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@cs.columbia.edu>

The current code for creating HYP mapping doesn't like to wrap
around zero, which prevents from mapping anything into the last
page of the virtual address space.

It doesn't take much effort to remove this limitation, making
the code more consistent with the rest of the kernel in the process.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@cs.columbia.edu>

The way we populate HYP mappings is a bit convoluted, to say the least.
Passing a pointer around to keep track of the current PFN is quite
odd, and we end-up having two different PTE accessors for no good
reason.

Simplify the whole thing by unifying the two PTE accessors, passing
a pgprot_t around, and moving the various validity checks to the
upper layers.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@cs.columbia.edu>

Instead of trying to free everything from PAGE_OFFSET to the
top of memory, use the virt_addr_valid macro to check the
upper limit.

Also do the same for the vmalloc region where the IO mappings
are allocated.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@cs.columbia.edu>

v8 is capable of invalidating Stage-2 by IPA, but v7 is not.
Change kvm_tlb_flush_vmid() to take an IPA parameter, which is
then ignored by the invalidation code (and nuke the whole TLB
as it always did).

This allows v8 to implement a more optimized strategy.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

Since the arm64 code doesn't have a global asm/idmap.h file, move
the inclusion to asm/kvm_mmu.h.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

The ARM ARM says that HPFAR reports bits [39:12] of the faulting
IPA, and we need to complement it with the bottom 12 bits of the
faulting VA.

This is always 12 bits, irrespective of the page size. Makes it
clearer in the code.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

__create_hyp_mappings() performs some kind of address validation before
creating the mapping, by verifying that the start address is above
PAGE_OFFSET.

This check is not completely correct for kernel memory (the upper
boundary has to be checked as well so we do not end up with highmem
pages), and wrong for IO mappings (the mapping must exist in the vmalloc
region).

Fix this by using the proper predicates (virt_addr_valid and
is_vmalloc_addr), which also work correctly on ARM64 (where the vmalloc
region is below PAGE_OFFSET).

Also change the BUG_ON() into a less agressive error return.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

arm64 cannot represent the kernel VAs in HYP mode, because of the lack
of TTBR1 at EL2. A way to cope with this situation is to have HYP VAs
to be an offset from the kernel VAs.

Introduce macros to convert a kernel VA to a HYP VA, make the HYP
mapping functions use these conversion macros. Also change the
documentation to reflect the existence of the offset.

On ARM, where we can have an identity mapping between kernel and HYP,
the macros are without any effect.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>