Using RCU for lockless shadow walking can increase the amount of memory
in use by the system, since RCU grace periods are unpredictable. We also
have an unconditional write to a shared variable (reader_counter), which
isn't good for scaling.
Replace that with a scheme similar to x86's get_user_pages_fast(): disable
interrupts during lockless shadow walk to force the freer
(kvm_mmu_commit_zap_page()) to wait for the TLB flush IPI to find the
processor with interrupts enabled.
We also add a new vcpu->mode, READING_SHADOW_PAGE_TABLES, to prevent
kvm_flush_remote_tlbs() from avoiding the IPI.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Its much cleaner to use PT_PAGE_TABLE_LEVEL than its numeric value.
Signed-off-by: Davidlohr Bueso <dave@gnu.org>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Iteration using rmap_next(), the actual body is pte_list_next(), is
inefficient: every time we call it we start from checking whether rmap
holds a single spte or points to a descriptor which links more sptes.
In the case of shadow paging, this quadratic total iteration cost is a
problem. Even for two dimensional paging, with EPT/NPT on, in which we
almost always have a single mapping, the extra checks at the end of the
iteration should be eliminated.
This patch fixes this by introducing rmap_iterator which keeps the
iteration context for the next search. Furthermore the implementation
of rmap_next() is splitted into two functions, rmap_get_first() and
rmap_get_next(), to avoid repeatedly checking whether the rmap being
iterated on has only one spte.
Although there seemed to be only a slight change for EPT/NPT, the actual
improvement was significant: we observed that GET_DIRTY_LOG for 1GB
dirty memory became 15% faster than before. This is probably because
the new code is easy to make branch predictions.
Note: we just remove pte_list_next() because we can think of parent_ptes
as a reverse mapping.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
We have PTE_LIST_EXT + 1 pointers in this structure and these 40/20
bytes do not fit cache lines well. Furthermore, some allocators may
use 64/32-byte objects for the pte_list_desc cache.
This patch solves this problem by changing PTE_LIST_EXT from 4 to 3.
For shadow paging, the new size is still large enough to hold both the
kernel and process mappings for usual anonymous pages. For file
mappings, there may be a slight change in the cache usage.
Note: with EPT/NPT we almost always have a single spte in each reverse
mapping and we will not see any change by this.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
Dropped such mappings when we enabled dirty logging and we will never
create new ones until we stop the logging.
For this we introduce a new function which can be used to write protect
a range of PT level pages: although we do not need to care about a range
of pages at this point, the following patch will need this feature to
optimize the write protection of many pages.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
We will use this in the following patch to implement another function
which needs to write protect pages using the rmap information.
Note that there is a small change in debug printing for large pages:
we do not differentiate them from others to avoid duplicating code.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
The reset_rsvds_bits_mask() function can use the guest walker's root level
number instead of using a separate 'level' variable.
Signed-off-by: Davidlohr Bueso <dave@gnu.org>
Signed-off-by: Avi Kivity <avi@redhat.com>
Some members of kvm_memory_slot are not used by every architecture.
This patch is the first step to make this difference clear by
introducing kvm_memory_slot::arch; lpage_info is moved into it.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This patch cleans up the code and removes the "(void)level;" warning
suppressor.
Note that we can also use this for PT_PAGE_TABLE_LEVEL to treat every
level uniformly later.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
We can remove the first ->nx state assignment since it is assigned afterwards anyways.
Signed-off-by: Davidlohr Bueso <dave@gnu.org>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
get_written_sptes is called twice in kvm_mmu_pte_write, one of them can be
removed
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
There is only one user of it and for_each_set_bit() does the same.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
module_param(bool) used to counter-intuitively take an int. In
fddd5201 (mid-2009) we allowed bool or int/unsigned int using a messy
trick.
It's time to remove the int/unsigned int option. For this version
it'll simply give a warning, but it'll break next kernel version.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
freed_pages is never evaluated, so remove it as well as the return code
kvm_mmu_remove_some_alloc_mmu_pages so far delivered to its only user.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
The unsync code should be stable now, maybe it is the time to remove this
parameter to cleanup the code a little bit
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Move the mmu code in kvm_arch_vcpu_init() to kvm_mmu_create()
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
The tracepoint is only used to audit mmu code, it should not be exposed to
user, let us replace it with jump-label.
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Introduce kvm_for_each_memslot to walk all valid memslot
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Currently, write protecting a slot needs to walk all the shadow pages
and checks ones which have a pte mapping a page in it.
The walk is overly heavy when dirty pages in that slot are not so many
and checking the shadow pages would result in unwanted cache pollution.
To mitigate this problem, we use rmap_write_protect() and check only
the sptes which can be reached from gfns marked in the dirty bitmap
when the number of dirty pages are less than that of shadow pages.
This criterion is reasonable in its meaning and worked well in our test:
write protection became some times faster than before when the ratio of
dirty pages are low and was not worse even when the ratio was near the
criterion.
Note that the locking for this write protection becomes fine grained.
The reason why this is safe is descripted in the comments.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
rmap_write_protect() calls gfn_to_rmap() for each level with gfn fixed.
This results in calling gfn_to_memslot() repeatedly with that gfn.
This patch introduces __gfn_to_rmap() which takes the slot as an
argument to avoid this.
This is also needed for the following dirty logging optimization.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
Remove redundant checks and use is_large_pte() macro.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
The host side pv mmu support has been marked for feature removal in
January 2011. It's not in use, is slower than shadow or hardware
assisted paging, and a maintenance burden. It's November 2011, time to
remove it.
Signed-off-by: Chris Wright <chrisw@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Detecting write-flooding does not work well, when we handle page written, if
the last speculative spte is not accessed, we treat the page is
write-flooding, however, we can speculative spte on many path, such as pte
prefetch, page synced, that means the last speculative spte may be not point
to the written page and the written page can be accessed via other sptes, so
depends on the Accessed bit of the last speculative spte is not enough
Instead of detected page accessed, we can detect whether the spte is accessed
after it is written, if the spte is not accessed but it is written frequently,
we treat is not a page table or it not used for a long time
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Sometimes, we only modify the last one byte of a pte to update status bit,
for example, clear_bit is used to clear r/w bit in linux kernel and 'andb'
instruction is used in this function, in this case, kvm_mmu_pte_write will
treat it as misaligned access, and the shadow page table is zapped
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
kvm_mmu_pte_write is too long, we split it for better readable
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
In kvm_mmu_pte_write, we do not need to alloc shadow page, so calling
kvm_mmu_free_some_pages is really unnecessary
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Fast prefetch spte for the unsync shadow page on invlpg path
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Directly Use mmu_page_zap_pte to zap spte in FNAME(invlpg), also remove the
same code between FNAME(invlpg) and FNAME(sync_page)
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
In current code, the accessed bit is always set when page fault occurred,
do not need to set it on pte write path
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
If the emulation is caused by #PF and it is non-page_table writing instruction,
it means the VM-EXIT is caused by shadow page protected, we can zap the shadow
page and retry this instruction directly
The idea is from Avi
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
kvm_mmu_pte_write is unsafe since we need to alloc pte_list_desc in the
function when spte is prefetched, unfortunately, we can not know how many
spte need to be prefetched on this path, that means we can use out of the
free pte_list_desc object in the cache, and BUG_ON() is triggered, also some
path does not fill the cache, such as INS instruction emulated that does not
trigger page fault
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Architecturally, PDPTEs are cached in the PDPTRs when CR3 is reloaded.
On SVM, it is not possible to implement this, but on VMX this is possible
and was indeed implemented until nested SVM changed this to unconditionally
read PDPTEs dynamically. This has noticable impact when running PAE guests.
Fix by changing the MMU to read PDPTRs from the cache, falling back to
reading from memory for the nested MMU.
Signed-off-by: Avi Kivity <avi@redhat.com>
Tested-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
__update_clear_spte_slow should return original spte while the
current code returns low half of original spte combined with high
half of new spte.
Signed-off-by: Zhao Jin <cronozhj@gmail.com>
Reviewed-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (43 commits)
fs: Merge split strings
treewide: fix potentially dangerous trailing ';' in #defined values/expressions
uwb: Fix misspelling of neighbourhood in comment
net, netfilter: Remove redundant goto in ebt_ulog_packet
trivial: don't touch files that are removed in the staging tree
lib/vsprintf: replace link to Draft by final RFC number
doc: Kconfig: `to be' -> `be'
doc: Kconfig: Typo: square -> squared
doc: Konfig: Documentation/power/{pm => apm-acpi}.txt
drivers/net: static should be at beginning of declaration
drivers/media: static should be at beginning of declaration
drivers/i2c: static should be at beginning of declaration
XTENSA: static should be at beginning of declaration
SH: static should be at beginning of declaration
MIPS: static should be at beginning of declaration
ARM: static should be at beginning of declaration
rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_check
Update my e-mail address
PCIe ASPM: forcedly -> forcibly
gma500: push through device driver tree
...
Fix up trivial conflicts:
- arch/arm/mach-ep93xx/dma-m2p.c (deleted)
- drivers/gpio/gpio-ep93xx.c (renamed and context nearby)
- drivers/net/r8169.c (just context changes)
The idea is from Avi:
| We could cache the result of a miss in an spte by using a reserved bit, and
| checking the page fault error code (or seeing if we get an ept violation or
| ept misconfiguration), so if we get repeated mmio on a page, we don't need to
| search the slot list/tree.
| (https://lkml.org/lkml/2011/2/22/221)
When the page fault is caused by mmio, we cache the info in the shadow page
table, and also set the reserved bits in the shadow page table, so if the mmio
is caused again, we can quickly identify it and emulate it directly
Searching mmio gfn in memslots is heavy since we need to walk all memeslots, it
can be reduced by this feature, and also avoid walking guest page table for
soft mmu.
[jan: fix operator precedence issue]
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Use rcu to protect shadow pages table to be freed, so we can safely walk it,
it should run fastly and is needed by mmio page fault
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Now, the spte is just from nonprsent to present or present to nonprsent, so
we can use some trick to set/clear spte non-atomicly as linux kernel does
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Introduce some interfaces to modify spte as linux kernel does:
- mmu_spte_clear_track_bits, it set the spte from present to nonpresent, and
track the stat bits(accessed/dirty) of spte
- mmu_spte_clear_no_track, the same as mmu_spte_clear_track_bits except
tracking the stat bits
- mmu_spte_set, set spte from nonpresent to present
- mmu_spte_update, only update the stat bits
Now, it does not allowed to set spte from present to present, later, we can
drop the atomicly opration for X86_32 host, and it is the preparing work to
get spte on X86_32 host out of the mmu lock
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Introduce handle_abnormal_pfn to handle fault pfn on page fault path,
introduce mmu_invalid_pfn to handle fault pfn on prefetch path
It is the preparing work for mmio page fault support
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
If the page fault is caused by mmio, the gfn can not be found in memslots, and
'bad_pfn' is returned on gfn_to_hva path, so we can use 'bad_pfn' to identify
the mmio page fault.
And, to clarify the meaning of mmio pfn, we return fault page instead of bad
page when the gfn is not allowd to prefetch
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
The idea is from Avi:
| Maybe it's time to kill off bypass_guest_pf=1. It's not as effective as
| it used to be, since unsync pages always use shadow_trap_nonpresent_pte,
| and since we convert between the two nonpresent_ptes during sync and unsync.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Split kvm_mmu_free_page to kvm_mmu_isolate_page and
kvm_mmu_free_page
One is used to remove the page from cache under mmu lock and the other is
used to free page table out of mmu lock
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Move counting used shadow pages from commiting path to preparing path to
reduce tlb flush on some paths
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
If 'pt_write' is true, we need to emulate the fault. And in later patch, we
need to emulate the fault even though it is not a pt_write event, so rename
it to better fit the meaning
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
If dirty bit is not set, we can make the pte access read-only to avoid handing
dirty bit everywhere
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
If the page fault is caused by mmio, we can cache the mmio info, later, we do
not need to walk guest page table and quickly know it is a mmio fault while we
emulate the mmio instruction
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Properly check the last mapping, and do not walk to the next level if last spte
is met
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This reverts commit bee931d31e588b8eb86b7edee32fac2d16930cd7.
TLB flush should be done lazily during guest entry, in
kvm_mmu_load().
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
kvm_set_cr0() and kvm_set_cr4(), and possible other functions,
assume that kvm_mmu_reset_context() flushes the guest TLB. However,
it does not.
Fix by flushing the tlb (and syncing the new root as well).
Signed-off-by: Avi Kivity <avi@redhat.com>
When CR0.WP=0, we sometimes map user pages as kernel pages (to allow
the kernel to write to them). Unfortunately this also allows the kernel
to fetch from these pages, even if CR4.SMEP is set.
Adjust for this by also setting NX on the spte in these circumstances.
Signed-off-by: Avi Kivity <avi@redhat.com>
Cleanup the same operation between kvm_mmu_page_unlink_children and
mmu_pte_write_zap_pte
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Parent pte rmap and page rmap are very similar, so use the same arithmetic
for them
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Abstract the operation of rmap to spte_list, then we can use it for the
reverse mapping of parent pte in the later patch
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Simply return from kvm_mmu_pte_write path if no shadow page is
write-protected, then we can avoid to walk all shadow pages and hold
mmu-lock
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Many stupid corrections of duplicated includes based on the output of
scripts/checkincludes.pl.
Signed-off-by: Vitaliy Ivanov <vitalivanov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
The condition is opposite, it always maps huge page for the dirty tracked page
Reported-by: Steve <stefan.bosak@gmail.com>
Signed-off-by: Steve <stefan.bosak@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Change each shrinker's API by consolidating the existing parameters into
shrink_control struct. This will simplify any further features added w/o
touching each file of shrinker.
[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: fix warning]
[kosaki.motohiro@jp.fujitsu.com: fix up new shrinker API]
[akpm@linux-foundation.org: fix xfs warning]
[akpm@linux-foundation.org: update gfs2]
Signed-off-by: Ying Han <yinghan@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The mmu_seq verification can be removed since we get the pfn in the
protection of mmu_lock.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This patch does:
- call vcpu->arch.mmu.update_pte directly
- use gfn_to_pfn_atomic in update_pte path
The suggestion is from Avi.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Cleanup the code of pte_prefetch_gfn_to_memslot and mapping_level_dirty_bitmap
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Using __get_free_page instead of alloc_page and page_address,
using free_page instead of __free_page and virt_to_page
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
No need to record the gfn to verifier the pte has the same mode as
current vcpu, it's because we only speculatively update the pte only
if the pte and vcpu have the same mode
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Set spte accessed bit only if guest_initiated == 1 that means the really
accessed
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Code under this lock requires non-preemptibility. Ensure this also over
-rt by converting it to raw spinlock.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Instead, drop large mappings, which were the reason we dropped shadow.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
For GRU and EPT, we need gup-fast to set referenced bit too (this is why
it's correct to return 0 when shadow_access_mask is zero, it requires
gup-fast to set the referenced bit). qemu-kvm access already sets the
young bit in the pte if it isn't zero-copy, if it's zero copy or a shadow
paging EPT minor fault we relay on gup-fast to signal the page is in
use...
We also need to check the young bits on the secondary pagetables for NPT
and not nested shadow mmu as the data may never get accessed again by the
primary pte.
Without this closer accuracy, we'd have to remove the heuristic that
avoids collapsing hugepages in hugepage virtual regions that have not even
a single subpage in use.
->test_young is full backwards compatible with GRU and other usages that
don't have young bits in pagetables set by the hardware and that should
nuke the secondary mmu mappings when ->clear_flush_young runs just like
EPT does.
Removing the heuristic that checks the young bit in
khugepaged/collapse_huge_page completely isn't so bad either probably but
I thought it was worth it and this makes it reliable.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This should work for both hugetlbfs and transparent hugepages.
[akpm@linux-foundation.org: bring forward PageTransCompound() addition for bisectability]
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the operation of 'writable' to set_spte() to clean up code
[avi: remove unneeded booleanification]
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
It only allows to audit one guest in the system since:
- 'audit_point' is a glob variable
- mmu_audit_disable() is called in kvm_mmu_destroy(), so audit is disabled
after a guest exited
this patch fix those issues then allow to audit more guests at the same time
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
If a pagetable contains a writeable large spte, all of its sptes will be
write protected, including non-leaf ones, leading to endless pagefaults.
Do not write protect pages above PT_PAGE_TABLE_LEVEL, as the spte fault
paths assume non-leaf sptes are writable.
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
In case of a nested page fault or an intercepted #PF newer SVM
implementations provide a copy of the faulting instruction bytes
in the VMCB.
Use these bytes to feed the instruction emulator and avoid the costly
guest instruction fetch in this case.
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
emulate_instruction had many callers, but only one used all
parameters. One parameter was unused, another one is now
hidden by a wrapper function (required for a future addition
anyway), so most callers use now a shorter parameter list.
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Large page information has two elements but one of them, write_count, alone
is accessed by a helper function.
This patch replaces this helper function with more generic one which returns
newly named kvm_lpage_info structure and use it to access the other element
rmap_pde.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
Retry #PF for softmmu only when the current vcpu has the same cr3 as the time
when #PF occurs
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Retry #PF is the speculative path, so don't set the accessed bit
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
It's the speculative path if 'no_apf = 1' and we will specially handle this
speculative path in the later patch, so 'prefault' is better to fit the sense.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
One more "KVM: MMU: Don't drop accessed bit while updating an spte."
Sptes are accessed by both kvm and hardware.
This patch uses update_spte() to fix the way of removing write access.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
Currently page fault cr2 and nesting infomation are carried outside
the fault data structure. Instead they are placed in the vcpu struct,
which results in confusion as global variables are manipulated instead
of passing parameters.
Fix this issue by adding address and nested fields to struct x86_exception,
so this struct can carry all information associated with a fault.
Signed-off-by: Avi Kivity <avi@redhat.com>
Tested-by: Joerg Roedel <joerg.roedel@amd.com>
Tested-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Introduce a common function to map invalid gpte
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Remove it since we can judge it by using sp->unsync
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Rename it to fit its sense better
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
We just need flush tlb if overwrite a writable spte with a read-only one.
And we should move this operation to set_spte() for sync_page path
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
If apf is generated in L2 guest and is completed in L1 guest, it will
prefault this apf in L1 guest's mmu context.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
