We're using __get_free_pages with to allocate the guest's stage-2
PGD. The standard behaviour of this function is to return a set of
pages where only the head page has a valid refcount.

This behaviour gets us into trouble when we're trying to increment
the refcount on a non-head page:

page:ffff7c00cfb693c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000000()
page dumped because: VM_BUG_ON_PAGE((*({ __attribute__((unused)) typeof((&page->_count)->counter) __var = ( typeof((&page->_count)->counter)) 0; (volatile typeof((&page->_count)->counter) *)&((&page->_count)->counter); })) <= 0)
BUG: failure at include/linux/mm.h:548/get_page()!
Kernel panic - not syncing: BUG!
CPU: 1 PID: 1695 Comm: kvm-vcpu-0 Not tainted 4.0.0-rc1+ #3825
Hardware name: APM X-Gene Mustang board (DT)
Call trace:
[<ffff80000008a09c>] dump_backtrace+0x0/0x13c
[<ffff80000008a1e8>] show_stack+0x10/0x1c
[<ffff800000691da8>] dump_stack+0x74/0x94
[<ffff800000690d78>] panic+0x100/0x240
[<ffff8000000a0bc4>] stage2_get_pmd+0x17c/0x2bc
[<ffff8000000a1dc4>] kvm_handle_guest_abort+0x4b4/0x6b0
[<ffff8000000a420c>] handle_exit+0x58/0x180
[<ffff80000009e7a4>] kvm_arch_vcpu_ioctl_run+0x114/0x45c
[<ffff800000099df4>] kvm_vcpu_ioctl+0x2e0/0x754
[<ffff8000001c0a18>] do_vfs_ioctl+0x424/0x5c8
[<ffff8000001c0bfc>] SyS_ioctl+0x40/0x78
CPU0: stopping

A possible approach for this is to split the compound page using
split_page() at allocation time, and change the teardown path to
free one page at a time.  It turns out that alloc_pages_exact() and
free_pages_exact() does exactly that.

While we're at it, the PGD allocation code is reworked to reduce
duplication.

This has been tested on an X-Gene platform with a 4kB/48bit-VA host
kernel, and kvmtool hacked to place memory in the second page of
the hardware PGD (PUD for the host kernel). Also regression-tested
on a Cubietruck (Cortex-A7).

 [ Reworked to use alloc_pages_exact() and free_pages_exact() and to
   return pointers directly instead of by reference as arguments
    - Christoffer ]
Reported-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

When handling a fault in stage-2, we need to resync I$ and D$, just
to be sure we don't leave any old cache line behind.

That's very good, except that we do so using the *user* address.
Under heavy load (swapping like crazy), we may end up in a situation
where the page gets mapped in stage-2 while being unmapped from
userspace by another CPU.

At that point, the DC/IC instructions can generate a fault, which
we handle with kvm->mmu_lock held. The box quickly deadlocks, user
is unhappy.

Instead, perform this invalidation through the kernel mapping,
which is guaranteed to be present. The box is much happier, and so
am I.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Let's assume a guest has created an uncached mapping, and written
to that page. Let's also assume that the host uses a cache-coherent
IO subsystem. Let's finally assume that the host is under memory
pressure and starts to swap things out.

Before this "uncached" page is evicted, we need to make sure
we invalidate potential speculated, clean cache lines that are
sitting there, or the IO subsystem is going to swap out the
cached view, loosing the data that has been written directly
into memory.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Trying to emulate the behaviour of set/way cache ops is fairly
pointless, as there are too many ways we can end-up missing stuff.
Also, there is some system caches out there that simply ignore
set/way operations.

So instead of trying to implement them, let's convert it to VA ops,
and use them as a way to re-enable the trapping of VM ops. That way,
we can detect the point when the MMU/caches are turned off, and do
a full VM flush (which is what the guest was trying to do anyway).

This allows a 32bit zImage to boot on the APM thingy, and will
probably help bootloaders in general.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

We don't have to write protect guest memory for dirty logging if architecture
supports hardware dirty logging, such as PML on VMX, so rename it to be more
generic.
Signed-off-by: NKai Huang <kai.huang@linux.intel.com>
Reviewed-by: NXiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

A comment in the dirty page logging patch series mentioned incorrectly
spelled config symbols, just fix them up to match the real thing.
Reported-by: NPaul Bolle <pebolle@tiscali.nl>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

This patch enables ARMv8 ditry page logging support. Plugs ARMv8 into generic
layer through Kconfig symbol, and drops earlier ARM64 constraints to enable
logging at architecture layer.
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMario Smarduch <m.smarduch@samsung.com>

This patch adds support for 2nd stage page fault handling while dirty page
logging. On huge page faults, huge pages are dissolved to normal pages, and
rebuilding of 2nd stage huge pages is blocked. In case migration is
canceled this restriction is removed and huge pages may be rebuilt again.
Signed-off-by: NMario Smarduch <m.smarduch@samsung.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>

Add support to track dirty pages between user space KVM_GET_DIRTY_LOG ioctl
calls. We call kvm_get_dirty_log_protect() function to do most of the work.
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NMario Smarduch <m.smarduch@samsung.com>

Add support for initial write protection of VM memslots. This patch
series assumes that huge PUDs will not be used in 2nd stage tables, which is
always valid on ARMv7
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMario Smarduch <m.smarduch@samsung.com>

Introduce a new function to unmap user RAM regions in the stage2 page
tables.  This is needed on reboot (or when the guest turns off the MMU)
to ensure we fault in pages again and make the dcache, RAM, and icache
coherent.

Using unmap_stage2_range for the whole guest physical range does not
work, because that unmaps IO regions (such as the GIC) which will not be
recreated or in the best case faulted in on a page-by-page basis.

Call this function on secondary and subsequent calls to the
KVM_ARM_VCPU_INIT ioctl so that a reset VCPU will detect the guest
Stage-1 MMU is off when faulting in pages and make the caches coherent.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Instead of using kvm_is_mmio_pfn() to decide whether a host region
should be stage 2 mapped with device attributes, add a new static
function kvm_is_device_pfn() that disregards RAM pages with the
reserved bit set, as those should usually not be mapped as device
memory.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Currently if using a 48-bit VA, tearing down the hyp page tables (which
can happen in the absence of a GICH or GICV resource) results in the
rather nasty splat below, evidently becasue we access a table that
doesn't actually exist.

Commit 38f791a4 (arm64: KVM: Implement 48 VA support for KVM EL2
and Stage-2) added a pgd_none check to __create_hyp_mappings to account
for the additional level of tables, but didn't add a corresponding check
to unmap_range, and this seems to be the source of the problem.

This patch adds the missing pgd_none check, ensuring we don't try to
access tables that don't exist.

Original splat below:

kvm [1]: Using HYP init bounce page @83fe94a000
kvm [1]: Cannot obtain GICH resource
Unable to handle kernel paging request at virtual address ffff7f7fff000000
pgd = ffff800000770000
[ffff7f7fff000000] *pgd=0000000000000000
Internal error: Oops: 96000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 1 Comm: swapper/0 Not tainted 3.18.0-rc2+ #89
task: ffff8003eb500000 ti: ffff8003eb45c000 task.ti: ffff8003eb45c000
PC is at unmap_range+0x120/0x580
LR is at free_hyp_pgds+0xac/0xe4
pc : [<ffff80000009b768>] lr : [<ffff80000009cad8>] pstate: 80000045
sp : ffff8003eb45fbf0
x29: ffff8003eb45fbf0 x28: ffff800000736000
x27: ffff800000735000 x26: ffff7f7fff000000
x25: 0000000040000000 x24: ffff8000006f5000
x23: 0000000000000000 x22: 0000007fffffffff
x21: 0000800000000000 x20: 0000008000000000
x19: 0000000000000000 x18: ffff800000648000
x17: ffff800000537228 x16: 0000000000000000
x15: 000000000000001f x14: 0000000000000000
x13: 0000000000000001 x12: 0000000000000020
x11: 0000000000000062 x10: 0000000000000006
x9 : 0000000000000000 x8 : 0000000000000063
x7 : 0000000000000018 x6 : 00000003ff000000
x5 : ffff800000744188 x4 : 0000000000000001
x3 : 0000000040000000 x2 : ffff800000000000
x1 : 0000007fffffffff x0 : 000000003fffffff

Process swapper/0 (pid: 1, stack limit = 0xffff8003eb45c058)
Stack: (0xffff8003eb45fbf0 to 0xffff8003eb460000)
fbe0:                                     eb45fcb0 ffff8003 0009cad8 ffff8000
fc00: 00000000 00000080 00736140 ffff8000 00736000 ffff8000 00000000 00007c80
fc20: 00000000 00000080 006f5000 ffff8000 00000000 00000080 00743000 ffff8000
fc40: 00735000 ffff8000 006d3030 ffff8000 006fe7b8 ffff8000 00000000 00000080
fc60: ffffffff 0000007f fdac1000 ffff8003 fd94b000 ffff8003 fda47000 ffff8003
fc80: 00502b40 ffff8000 ff000000 ffff7f7f fdec6000 00008003 fdac1630 ffff8003
fca0: eb45fcb0 ffff8003 ffffffff 0000007f eb45fd00 ffff8003 0009b378 ffff8000
fcc0: ffffffea 00000000 006fe000 ffff8000 00736728 ffff8000 00736120 ffff8000
fce0: 00000040 00000000 00743000 ffff8000 006fe7b8 ffff8000 0050cd48 00000000
fd00: eb45fd60 ffff8003 00096070 ffff8000 006f06e0 ffff8000 006f06e0 ffff8000
fd20: fd948b40 ffff8003 0009a320 ffff8000 00000000 00000000 00000000 00000000
fd40: 00000ae0 00000000 006aa25c ffff8000 eb45fd60 ffff8003 0017ca44 00000002
fd60: eb45fdc0 ffff8003 0009a33c ffff8000 006f06e0 ffff8000 006f06e0 ffff8000
fd80: fd948b40 ffff8003 0009a320 ffff8000 00000000 00000000 00735000 ffff8000
fda0: 006d3090 ffff8000 006aa25c ffff8000 00735000 ffff8000 006d3030 ffff8000
fdc0: eb45fdd0 ffff8003 000814c0 ffff8000 eb45fe50 ffff8003 006aaac4 ffff8000
fde0: 006ddd90 ffff8000 00000006 00000000 006d3000 ffff8000 00000095 00000000
fe00: 006a1e90 ffff8000 00735000 ffff8000 006d3000 ffff8000 006aa25c ffff8000
fe20: 00735000 ffff8000 006d3030 ffff8000 eb45fe50 ffff8003 006fac68 ffff8000
fe40: 00000006 00000006 fe293ee6 ffff8003 eb45feb0 ffff8003 004f8ee8 ffff8000
fe60: 004f8ed4 ffff8000 00735000 ffff8000 00000000 00000000 00000000 00000000
fe80: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
fea0: 00000000 00000000 00000000 00000000 00000000 00000000 000843d0 ffff8000
fec0: 004f8ed4 ffff8000 00000000 00000000 00000000 00000000 00000000 00000000
fee0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ff00: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ff20: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ff40: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ff60: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ff80: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ffa0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000005 00000000
ffe0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
Call trace:
[<ffff80000009b768>] unmap_range+0x120/0x580
[<ffff80000009cad4>] free_hyp_pgds+0xa8/0xe4
[<ffff80000009b374>] kvm_arch_init+0x268/0x44c
[<ffff80000009606c>] kvm_init+0x24/0x260
[<ffff80000009a338>] arm_init+0x18/0x24
[<ffff8000000814bc>] do_one_initcall+0x88/0x1a0
[<ffff8000006aaac0>] kernel_init_freeable+0x148/0x1e8
[<ffff8000004f8ee4>] kernel_init+0x10/0xd4
Code: 8b000263 92628479 d1000720 eb01001f (f9400340)
---[ end trace 3bc230562e926fa4 ]---
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jungseok Lee <jungseoklee85@gmail.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Readonly memslots are often used to implement emulation of ROMs and
NOR flashes, in which case the guest may legally map these regions as
uncached.
To deal with the incoherency associated with uncached guest mappings,
treat all readonly memslots as incoherent, and ensure that pages that
belong to regions tagged as such are flushed to DRAM before being passed
to the guest.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

To allow handling of incoherent memslots in a subsequent patch, this
patch adds a paramater 'ipa_uncached' to cache_coherent_guest_page()
so that we can instruct it to flush the page's contents to DRAM even
if the guest has caching globally enabled.
Signed-off-by: NLaszlo Ersek <lersek@redhat.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

Instead of using kvm_is_mmio_pfn() to decide whether a host region
should be stage 2 mapped with device attributes, add a new static
function kvm_is_device_pfn() that disregards RAM pages with the
reserved bit set, as those should usually not be mapped as device
memory.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

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>