Pull locking fixes from Ingo Molnar:
"Two fixes: the paravirt spin_unlock() corruption/crash fix, and an
rtmutex NULL dereference crash fix"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/spinlocks/paravirt: Fix memory corruption on unlock
locking/rtmutex: Avoid a NULL pointer dereference on deadlock
Paravirt spinlock clears slowpath flag after doing unlock.
As explained by Linus currently it does:
prev = *lock;
add_smp(&lock->tickets.head, TICKET_LOCK_INC);
/* add_smp() is a full mb() */
if (unlikely(lock->tickets.tail & TICKET_SLOWPATH_FLAG))
__ticket_unlock_slowpath(lock, prev);
which is *exactly* the kind of things you cannot do with spinlocks,
because after you've done the "add_smp()" and released the spinlock
for the fast-path, you can't access the spinlock any more. Exactly
because a fast-path lock might come in, and release the whole data
structure.
Linus suggested that we should not do any writes to lock after unlock(),
and we can move slowpath clearing to fastpath lock.
So this patch implements the fix with:
1. Moving slowpath flag to head (Oleg):
Unlocked locks don't care about the slowpath flag; therefore we can keep
it set after the last unlock, and clear it again on the first (try)lock.
-- this removes the write after unlock. note that keeping slowpath flag would
result in unnecessary kicks.
By moving the slowpath flag from the tail to the head ticket we also avoid
the need to access both the head and tail tickets on unlock.
2. use xadd to avoid read/write after unlock that checks the need for
unlock_kick (Linus):
We further avoid the need for a read-after-release by using xadd;
the prev head value will include the slowpath flag and indicate if we
need to do PV kicking of suspended spinners -- on modern chips xadd
isn't (much) more expensive than an add + load.
Result:
setup: 16core (32 cpu +ht sandy bridge 8GB 16vcpu guest)
benchmark overcommit %improve
kernbench 1x -0.13
kernbench 2x 0.02
dbench 1x -1.77
dbench 2x -0.63
[Jeremy: Hinted missing TICKET_LOCK_INC for kick]
[Oleg: Moved slowpath flag to head, ticket_equals idea]
[PeterZ: Added detailed changelog]
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Jones <drjones@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Jones <davej@redhat.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Fernando Luis Vázquez Cao <fernando_b1@lab.ntt.co.jp>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: a.ryabinin@samsung.com
Cc: dave@stgolabs.net
Cc: hpa@zytor.com
Cc: jasowang@redhat.com
Cc: jeremy@goop.org
Cc: paul.gortmaker@windriver.com
Cc: riel@redhat.com
Cc: tglx@linutronix.de
Cc: waiman.long@hp.com
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20150215173043.GA7471@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 perf updates from Ingo Molnar:
"This series tightens up RDPMC permissions: currently even highly
sandboxed x86 execution environments (such as seccomp) have permission
to execute RDPMC, which may leak various perf events / PMU state such
as timing information and other CPU execution details.
This 'all is allowed' RDPMC mode is still preserved as the
(non-default) /sys/devices/cpu/rdpmc=2 setting. The new default is
that RDPMC access is only allowed if a perf event is mmap-ed (which is
needed to correctly interpret RDPMC counter values in any case).
As a side effect of these changes CR4 handling is cleaned up in the
x86 code and a shadow copy of the CR4 value is added.
The extra CR4 manipulation adds ~ <50ns to the context switch cost
between rdpmc-capable and rdpmc-non-capable mms"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86: Add /sys/devices/cpu/rdpmc=2 to allow rdpmc for all tasks
perf/x86: Only allow rdpmc if a perf_event is mapped
perf: Pass the event to arch_perf_update_userpage()
perf: Add pmu callbacks to track event mapping and unmapping
x86: Add a comment clarifying LDT context switching
x86: Store a per-cpu shadow copy of CR4
x86: Clean up cr4 manipulation
This series tightens the rules for ACCESS_ONCE to only work
on scalar types. It also contains the necessary fixups as
indicated by build bots of linux-next.
Now everything is in place to prevent new non-scalar users
of ACCESS_ONCE and we can continue to convert code to
READ_ONCE/WRITE_ONCE.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux
Pull ACCESS_ONCE() rule tightening from Christian Borntraeger:
"Tighten rules for ACCESS_ONCE
This series tightens the rules for ACCESS_ONCE to only work on scalar
types. It also contains the necessary fixups as indicated by build
bots of linux-next. Now everything is in place to prevent new
non-scalar users of ACCESS_ONCE and we can continue to convert code to
READ_ONCE/WRITE_ONCE"
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux:
kernel: Fix sparse warning for ACCESS_ONCE
next: sh: Fix compile error
kernel: tighten rules for ACCESS ONCE
mm/gup: Replace ACCESS_ONCE with READ_ONCE
x86/spinlock: Leftover conversion ACCESS_ONCE->READ_ONCE
x86/xen/p2m: Replace ACCESS_ONCE with READ_ONCE
ppc/hugetlbfs: Replace ACCESS_ONCE with READ_ONCE
ppc/kvm: Replace ACCESS_ONCE with READ_ONCE
CR4 manipulation was split, seemingly at random, between direct
(write_cr4) and using a helper (set/clear_in_cr4). Unfortunately,
the set_in_cr4 and clear_in_cr4 helpers also poke at the boot code,
which only a small subset of users actually wanted.
This patch replaces all cr4 access in functions that don't leave cr4
exactly the way they found it with new helpers cr4_set_bits,
cr4_clear_bits, and cr4_set_bits_and_update_boot.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Vince Weaver <vince@deater.net>
Cc: "hillf.zj" <hillf.zj@alibaba-inc.com>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/495a10bdc9e67016b8fd3945700d46cfd5c12c2f.1414190806.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use the "foreign" page flag to mark pages that have a grant map. Use
page->private to store information of the grant (the granting domain
and the grant reference).
Signed-off-by: Jennifer Herbert <jennifer.herbert@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Ballooned pages are always used for grant maps which means the
original frame does not need to be saved in page->index nor restored
after the grant unmap.
This allows the workaround in netback for the conflicting use of the
(unionized) page->index and page->pfmemalloc to be removed.
Signed-off-by: Jennifer Herbert <jennifer.herbert@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
The scratch frame mappings for ballooned pages and the m2p override
are broken. Remove them in preparation for replacing them with
simpler mechanisms that works.
The scratch pages did not ensure that the page was not in use. In
particular, the foreign page could still be in use by hardware. If
the guest reused the frame the hardware could read or write that
frame.
The m2p override did not handle the same frame being granted by two
different grant references. Trying an M2P override lookup in this
case is impossible.
With the m2p override removed, the grant map/unmap for the kernel
mappings (for x86 PV) can be easily batched in
set_foreign_p2m_mapping() and clear_foreign_p2m_mapping().
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
When unmapping grants, instead of converting the kernel map ops to
unmap ops on the fly, pre-populate the set of unmap ops.
This allows the grant unmap for the kernel mappings to be trivially
batched in the future.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
The file arch/x86/xen/mmu.c has some functions that can be annotated
with "__init".
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Some more functions in arch/x86/xen/setup.c can be made "__init".
xen_ignore_unusable() can be made "static".
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
In many places in arch/x86/xen/setup.c wrong types are used for
physical addresses (u64 or unsigned long long). Use phys_addr_t
instead.
Use macros already defined instead of open coding them.
Correct some other type mismatches.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Remove extern declarations in arch/x86/xen/setup.c which are either
not used or redundant. Move needed other extern declarations to
xen-ops.h
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Call __set_current_state() instead of assigning the new state directly.
These interfaces also aid CONFIG_DEBUG_ATOMIC_SLEEP environments,
keeping track of who changed the state.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
In Dom0's the use of the TSC clocksource (whenever it is stable enough to
be used) instead of the Xen clocksource should not cause any issues, as
Dom0 VMs never live-migrated. The TSC clocksource is somewhat more
efficient than the Xen paravirtualised clocksource, thus it should have
higher rating.
This patch decreases the rating of the Xen clocksource in Dom0s to 275.
Which is half-way between the rating of the TSC clocksource (300) and the
hpet clocksource (250).
Cc: Anthony Liguori <aliguori@amazon.com>
Signed-off-by: Imre Palik <imrep@amazon.de>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
ACCESS_ONCE does not work reliably on non-scalar types. For
example gcc 4.6 and 4.7 might remove the volatile tag for such
accesses during the SRA (scalar replacement of aggregates) step
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145)
Change the p2m code to replace ACCESS_ONCE with READ_ONCE.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>
- Several critical linear p2m fixes that prevented some hosts from
booting.
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Merge tag 'stable/for-linus-3.19-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen bug fixes from David Vrabel:
"Several critical linear p2m fixes that prevented some hosts from
booting"
* tag 'stable/for-linus-3.19-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
x86/xen: properly retrieve NMI reason
xen: check for zero sized area when invalidating memory
xen: use correct type for physical addresses
xen: correct race in alloc_p2m_pmd()
xen: correct error for building p2m list on 32 bits
x86/xen: avoid freeing static 'name' when kasprintf() fails
x86/xen: add extra memory for remapped frames during setup
x86/xen: don't count how many PFNs are identity mapped
x86/xen: Free bootmem in free_p2m_page() during early boot
x86/xen: Remove unnecessary BUG_ON(preemptible()) in xen_setup_timer()
Using the native code here can't work properly, as the hypervisor would
normally have cleared the two reason bits by the time Dom0 gets to see
the NMI (if passed to it at all). There's a shared info field for this,
and there's an existing hook to use - just fit the two together. This
is particularly relevant so that NMIs intended to be handled by APEI /
GHES actually make it to the respective handler.
Note that the hook can (and should) be used irrespective of whether
being in Dom0, as accessing port 0x61 in a DomU would be even worse,
while the shared info field would just hold zero all the time. Note
further that hardware NMI handling for PVH doesn't currently work
anyway due to missing code in the hypervisor (but it is expected to
work the native rather than the PV way).
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
With the introduction of the linear mapped p2m list setting memory
areas to "invalid" had to be delayed. When doing the invalidation
make sure no zero sized areas are processed.
Signed-off-by: Juegren Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
When converting a pfn to a physical address be sure to use 64 bit
wide types or convert the physical address to a pfn if possible.
Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
When allocating a new pmd for the linear mapped p2m list a check is
done for not introducing another pmd when this just happened on
another cpu. In this case the old pte pointer was returned which
points to the p2m_missing or p2m_identity page. The correct value
would be the pointer to the found new page.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
In xen_rebuild_p2m_list() for large areas of invalid or identity
mapped memory the pmd entries on 32 bit systems are initialized
wrong. Correct this error.
Suggested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
In case kasprintf() fails in xen_setup_timer() we assign name to the
static string "<timer kasprintf failed>". We, however, don't check
that fact before issuing kfree() in xen_teardown_timer(), kernel is
supposed to crash with 'kernel BUG at mm/slub.c:3341!'
Solve the issue by making name a fixed length string inside struct
xen_clock_event_device. 16 bytes should be enough.
Suggested-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
If the non-RAM regions in the e820 memory map are larger than the size
of the initial balloon, a BUG was triggered as the frames are remaped
beyond the limit of the linear p2m. The frames are remapped into the
initial balloon area (xen_extra_mem) but not enough of this is
available.
Ensure enough extra memory regions are added for these remapped
frames.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
This accounting is just used to print a diagnostic message that isn't
very useful.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
With recent changes in p2m we now have legitimate cases when
p2m memory needs to be freed during early boot (i.e. before
slab is initialized).
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
There is no reason for having it and, with commit 250a1ac685 ("x86,
smpboot: Remove pointless preempt_disable() in
native_smp_prepare_cpus()"), it prevents HVM guests from booting.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
- Linear p2m for x86 PV guests which simplifies the p2m code, improves
performance and will allow for > 512 GB PV guests in the future.
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Merge tag 'stable/for-linus-3.19-rc0b-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull additional xen update from David Vrabel:
"Xen: additional features for 3.19-rc0
- Linear p2m for x86 PV guests which simplifies the p2m code,
improves performance and will allow for > 512 GB PV guests in the
future.
A last-minute, configuration specific issue was discovered with this
change which is why it was not included in my previous pull request.
This is now been fixed and tested"
* tag 'stable/for-linus-3.19-rc0b-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen: switch to post-init routines in xen mmu.c earlier
Revert "swiotlb-xen: pass dev_addr to swiotlb_tbl_unmap_single"
xen: annotate xen_set_identity_and_remap_chunk() with __init
xen: introduce helper functions to do safe read and write accesses
xen: Speed up set_phys_to_machine() by using read-only mappings
xen: switch to linear virtual mapped sparse p2m list
xen: Hide get_phys_to_machine() to be able to tune common path
x86: Introduce function to get pmd entry pointer
xen: Delay invalidating extra memory
xen: Delay m2p_override initialization
xen: Delay remapping memory of pv-domain
xen: use common page allocation function in p2m.c
xen: Make functions static
xen: fix some style issues in p2m.c
With the virtual mapped linear p2m list the post-init mmu operations
must be used for setting up the p2m mappings, as in case of
CONFIG_FLATMEM the init routines may trigger BUGs.
paging_init() sets up all infrastructure needed to switch to the
post-init mmu ops done by xen_post_allocator_init(). With the virtual
mapped linear p2m list we need some mmu ops during setup of this list,
so we have to switch to the correct mmu ops as soon as possible.
The p2m list is usable from the beginning, just expansion requires to
have established the new linear mapping. So the call of
xen_remap_memory() had to be introduced, but this is not due to the
mmu ops requiring this.
Summing it up: calling xen_post_allocator_init() not directly after
paging_init() was conceptually wrong in the beginning, it just didn't
matter up to now as no functions used between the two calls needed
some critical mmu ops (e.g. alloc_pte). This has changed now, so I
corrected it.
Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Pull x86 vdso updates from Ingo Molnar:
"Various vDSO updates from Andy Lutomirski, mostly cleanups and
reorganization to improve maintainability, but also some
micro-optimizations and robustization changes"
* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86_64/vsyscall: Restore orig_ax after vsyscall seccomp
x86_64: Add a comment explaining the TASK_SIZE_MAX guard page
x86_64,vsyscall: Make vsyscall emulation configurable
x86_64, vsyscall: Rewrite comment and clean up headers in vsyscall code
x86_64, vsyscall: Turn vsyscalls all the way off when vsyscall==none
x86,vdso: Use LSL unconditionally for vgetcpu
x86: vdso: Fix build with older gcc
x86_64/vdso: Clean up vgetcpu init and merge the vdso initcalls
x86_64/vdso: Remove jiffies from the vvar page
x86/vdso: Make the PER_CPU segment 32 bits
x86/vdso: Make the PER_CPU segment start out accessed
x86/vdso: Change the PER_CPU segment to use struct desc_struct
x86_64/vdso: Move getcpu code from vsyscall_64.c to vdso/vma.c
x86_64/vsyscall: Move all of the gate_area code to vsyscall_64.c
Pull x86 mm tree changes from Ingo Molnar:
"The biggest change is full PAT support from Jürgen Gross:
The x86 architecture offers via the PAT (Page Attribute Table) a
way to specify different caching modes in page table entries. The
PAT MSR contains 8 entries each specifying one of 6 possible cache
modes. A pte references one of those entries via 3 bits:
_PAGE_PAT, _PAGE_PWT and _PAGE_PCD.
The Linux kernel currently supports only 4 different cache modes.
The PAT MSR is set up in a way that the setting of _PAGE_PAT in a
pte doesn't matter: the top 4 entries in the PAT MSR are the same
as the 4 lower entries.
This results in the kernel not supporting e.g. write-through mode.
Especially this cache mode would speed up drivers of video cards
which now have to use uncached accesses.
OTOH some old processors (Pentium) don't support PAT correctly and
the Xen hypervisor has been using a different PAT MSR configuration
for some time now and can't change that as this setting is part of
the ABI.
This patch set abstracts the cache mode from the pte and introduces
tables to translate between cache mode and pte bits (the default
cache mode "write back" is hard-wired to PAT entry 0). The tables
are statically initialized with values being compatible to old
processors and current usage. As soon as the PAT MSR is changed
(or - in case of Xen - is read at boot time) the tables are changed
accordingly. Requests of mappings with special cache modes are
always possible now, in case they are not supported there will be a
fallback to a compatible but slower mode.
Summing it up, this patch set adds the following features:
- capability to support WT and WP cache modes on processors with
full PAT support
- processors with no or uncorrect PAT support are still working as
today, even if WT or WP cache mode are selected by drivers for
some pages
- reduction of Xen special handling regarding cache mode
Another change is a boot speedup on ridiculously large RAM systems,
plus other smaller fixes"
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
x86: mm: Move PAT only functions to mm/pat.c
xen: Support Xen pv-domains using PAT
x86: Enable PAT to use cache mode translation tables
x86: Respect PAT bit when copying pte values between large and normal pages
x86: Support PAT bit in pagetable dump for lower levels
x86: Clean up pgtable_types.h
x86: Use new cache mode type in memtype related functions
x86: Use new cache mode type in mm/ioremap.c
x86: Use new cache mode type in setting page attributes
x86: Remove looking for setting of _PAGE_PAT_LARGE in pageattr.c
x86: Use new cache mode type in track_pfn_remap() and track_pfn_insert()
x86: Use new cache mode type in mm/iomap_32.c
x86: Use new cache mode type in asm/pgtable.h
x86: Use new cache mode type in arch/x86/mm/init_64.c
x86: Use new cache mode type in arch/x86/pci
x86: Use new cache mode type in drivers/video/fbdev/vermilion
x86: Use new cache mode type in drivers/video/fbdev/gbefb.c
x86: Use new cache mode type in include/asm/fb.h
x86: Make page cache mode a real type
x86: mm: Use 2GB memory block size on large-memory x86-64 systems
...
Commit 5b8e7d8054 removed the __init
annotation from xen_set_identity_and_remap_chunk(). Add it again.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Introduce two helper functions to safely read and write unsigned long
values from or to memory when the access may fault because the mapping
is non-present or read-only.
These helpers can be used instead of open coded uses of __get_user()
and __put_user() avoiding the need to do casts to fix sparse warnings.
Use the helpers in page.h and p2m.c. This will fix the sparse
warnings when doing "make C=1".
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Instead of checking at each call of set_phys_to_machine() whether a
new p2m page has to be allocated due to writing an entry in a large
invalid or identity area, just map those areas read only and react
to a page fault on write by allocating the new page.
This change will make the common path with no allocation much
faster as it only requires a single write of the new mfn instead
of walking the address translation tables and checking for the
special cases.
Suggested-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
At start of the day the Xen hypervisor presents a contiguous mfn list
to a pv-domain. In order to support sparse memory this mfn list is
accessed via a three level p2m tree built early in the boot process.
Whenever the system needs the mfn associated with a pfn this tree is
used to find the mfn.
Instead of using a software walked tree for accessing a specific mfn
list entry this patch is creating a virtual address area for the
entire possible mfn list including memory holes. The holes are
covered by mapping a pre-defined page consisting only of "invalid
mfn" entries. Access to a mfn entry is possible by just using the
virtual base address of the mfn list and the pfn as index into that
list. This speeds up the (hot) path of determining the mfn of a
pfn.
Kernel build on a Dell Latitude E6440 (2 cores, HT) in 64 bit Dom0
showed following improvements:
Elapsed time: 32:50 -> 32:35
System: 18:07 -> 17:47
User: 104:00 -> 103:30
Tested with following configurations:
- 64 bit dom0, 8GB RAM
- 64 bit dom0, 128 GB RAM, PCI-area above 4 GB
- 32 bit domU, 512 MB, 8 GB, 43 GB (more wouldn't work even without
the patch)
- 32 bit domU, ballooning up and down
- 32 bit domU, save and restore
- 32 bit domU with PCI passthrough
- 64 bit domU, 8 GB, 2049 MB, 5000 MB
- 64 bit domU, ballooning up and down
- 64 bit domU, save and restore
- 64 bit domU with PCI passthrough
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Today get_phys_to_machine() is always called when the mfn for a pfn
is to be obtained. Add a wrapper __pfn_to_mfn() as inline function
to be able to avoid calling get_phys_to_machine() when possible as
soon as the switch to a linear mapped p2m list has been done.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
When the physical memory configuration is initialized the p2m entries
for not pouplated memory pages are set to "invalid". As those pages
are beyond the hypervisor built p2m list the p2m tree has to be
extended.
This patch delays processing the extra memory related p2m entries
during the boot process until some more basic memory management
functions are callable. This removes the need to create new p2m
entries until virtual memory management is available.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
The m2p overrides are used to be able to find the local pfn for a
foreign mfn mapped into the domain. They are used by driver backends
having to access frontend data.
As this functionality isn't used in early boot it makes no sense to
initialize the m2p override functions very early. It can be done
later without doing any harm, removing the need for allocating memory
via extend_brk().
While at it make some m2p override functions static as they are only
used internally.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Early in the boot process the memory layout of a pv-domain is changed
to match the E820 map (either the host one for Dom0 or the Xen one)
regarding placement of RAM and PCI holes. This requires removing memory
pages initially located at positions not suitable for RAM and adding
them later at higher addresses where no restrictions apply.
To be able to operate on the hypervisor supported p2m list until a
virtual mapped linear p2m list can be constructed, remapping must
be delayed until virtual memory management is initialized, as the
initial p2m list can't be extended unlimited at physical memory
initialization time due to it's fixed structure.
A further advantage is the reduction in complexity and code volume as
we don't have to be careful regarding memory restrictions during p2m
updates.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
In arch/x86/xen/p2m.c three different allocation functions for
obtaining a memory page are used: extend_brk(), alloc_bootmem_align()
or __get_free_page(). Which of those functions is used depends on the
progress of the boot process of the system.
Introduce a common allocation routine selecting the to be called
allocation routine dynamically based on the boot progress. This allows
moving initialization steps without having to care about changing
allocation calls.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Some functions in arch/x86/xen/p2m.c are used locally only. Make them
static. Rearrange the functions in p2m.c to avoid forward declarations.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
The source arch/x86/xen/p2m.c has some coding style issues. Fix them.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Commit 2ed53c0d6c ("x86/smpboot: Speed up suspend/resume by
avoiding 100ms sleep for CPU offline during S3") introduced
completions to CPU offlining process. These completions are not
initialized on Xen kernels causing a panic in
play_dead_common().
Move handling of die_complete into common routines to make them
available to Xen guests.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: tianyu.lan@intel.com
Cc: konrad.wilk@oracle.com
Cc: xen-devel@lists.xenproject.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414770572-7950-1-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This adds CONFIG_X86_VSYSCALL_EMULATION, guarded by CONFIG_EXPERT.
Turning it off completely disables vsyscall emulation, saving ~3.5k
for vsyscall_64.c, 4k for vsyscall_emu_64.S (the fake vsyscall
page), some tiny amount of core mm code that supports a gate area,
and possibly 4k for a wasted pagetable. The latter is because the
vsyscall addresses are misaligned and fit poorly in the fixmap.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/r/406db88b8dd5f0cbbf38216d11be34bbb43c7eae.1414618407.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Panic if Xen provides a memory map with 0 entries. Although this is
unlikely, it is better to catch the error at the point of seeing the map
than later on as a symptom of some other crash.
Signed-off-by: Martin Kelly <martkell@amazon.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Commit 89cbc76768 ("x86: Replace __get_cpu_var uses") replaced
__get_cpu_var() with this_cpu_ptr() in xen_clocksource_read() in such a
way that instead of accessing a structure pointed to by a per-cpu pointer
we are trying to get to a per-cpu structure.
__this_cpu_read() of the pointer is the more appropriate accessor.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
When a new p2m leaf is allocated this leaf is linked into the p2m tree
via cmpxchg. Unfortunately the compare value for checking the success
of the update is read after checking for the need of a new leaf. It is
possible that a new leaf has been linked into the tree concurrently
in between. This could lead to a leaked memory page and to the loss of
some p2m entries.
Avoid the race by using the read compare value for checking the need
of a new p2m leaf and use ACCESS_ONCE() to get it.
There are other places which seem to need ACCESS_ONCE() to ensure
proper operation. Change them accordingly.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
The 3 level p2m tree for the Xen tools is constructed very early at
boot by calling xen_build_mfn_list_list(). Memory needed for this tree
is allocated via extend_brk().
As this tree (other than the kernel internal p2m tree) is only needed
for domain save/restore, live migration and crash dump analysis it
doesn't matter whether it is constructed very early or just some
milliseconds later when memory allocation is possible by other means.
This patch moves the call of xen_build_mfn_list_list() just after
calling xen_pagetable_p2m_copy() simplifying this function, too, as it
doesn't have to bother with two parallel trees now. The same applies
for some other internal functions.
While simplifying code, make early_can_reuse_p2m_middle() static and
drop the unused second parameter. p2m_mid_identity_mfn can be removed
as well, it isn't used either.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
