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>
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>
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>
This patch fix kvm-unit-tests hanging and incorrect PT_ACCESSED_MASK
bit set in the case of SMEP fault. The code updated 'eperm' after
the variable was checked.
Signed-off-by: Yang, Wei <wei.y.yang@intel.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>
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>
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>
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>
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>
gw->pte_access is the final access permission, since it is unified with
gw->pt_access when we walked guest page table:
FNAME(walk_addr_generic):
pte_access = pt_access & FNAME(gpte_access)(vcpu, pte, true);
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>
The current name does not explain the meaning well. So give it a better
name "retry_walk" to show that we are trying the walk again.
This was suggested by Ingo Molnar.
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Avoid two step jump to the error handling part. This eliminates the use
of the variables present and rsvd_fault.
We also use the const type qualifier to show that write/user/fetch_fault
do not change in the function.
Both of these were suggested by Ingo Molnar.
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
On 3.0-rc1 I get
In file included from arch/x86/kvm/mmu.c:2856:
arch/x86/kvm/paging_tmpl.h: In function ‘paging32_walk_addr_generic’:
arch/x86/kvm/paging_tmpl.h:124: warning: ‘ptep_user’ may be used uninitialized in this function
In file included from arch/x86/kvm/mmu.c:2852:
arch/x86/kvm/paging_tmpl.h: In function ‘paging64_walk_addr_generic’:
arch/x86/kvm/paging_tmpl.h:124: warning: ‘ptep_user’ may be used uninitialized in this function
caused by 6e2ca7d180. According to Takuya
Yoshikawa, ptep_user won't be used uninitialized so shut up gcc.
Cc: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Link: http://lkml.kernel.org/r/20110530094604.GC21833@liondog.tnic
Signed-off-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
The address of the gpte was already calculated and stored in ptep_user
before entering cmpxchg_gpte().
This patch makes cmpxchg_gpte() to use that to make it clear that we
are using the same address during walk_addr_generic().
Note that the unlikely annotations are used to show that the conditions
are something unusual rather than for performance.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This way, we can avoid checking the user space address many times when
we read the guest memory.
Although we can do the same for write if we check which slots are
writable, we do not care write now: reading the guest memory happens
more often than writing.
[avi: change VERIFY_READ to VERIFY_WRITE]
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
When we optimized walk_addr_generic() by not using the generic guest
memory reader, we replaced copy_from_user() with get_user():
commit e30d2a170506830d5eef5e9d7990c5aedf1b0a51
KVM: MMU: Optimize guest page table walk
commit 15e2ac9a43d4d7d08088e404fddf2533a8e7d52e
KVM: MMU: Fix 64-bit paging breakage on x86_32
But as Andi pointed out later, copy_from_user() does the same as
get_user() as long as we give a constant size to it.
So we use copy_from_user() to clean up the code.
The only, noticeable, regression introduced by this is 64-bit gpte
reading on x86_32 hosts needed for PAE guests.
But this can be mitigated by implementing 8-byte get_user() for x86_32,
if needed.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
Fix regression introduced by
commit e30d2a170506830d5eef5e9d7990c5aedf1b0a51
KVM: MMU: Optimize guest page table walk
On x86_32, get_user() does not support 64-bit values and we fail to
build KVM at the point of 64-bit paging.
This patch fixes this by using get_user() twice for that condition.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Reported-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
walk_addr_generic() is a hot path and is also hard for the cpu to predict -
some of the parameters (fetch_fault in particular) vary wildly from
invocation to invocation.
Add unlikely() annotations where appropriate; all walk failures are
considered unlikely, as are cases where we have to mark the accessed or
dirty bit, as they are slow paths both in kvm and on real processors.
Signed-off-by: Avi Kivity <avi@redhat.com>
This patch optimizes the guest page table walk by using get_user()
instead of copy_from_user().
With this patch applied, paging64_walk_addr_generic() has become
about 0.5us to 1.0us faster on my Phenom II machine with NPT on.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
This patch makes the cmpxchg_gpte() function aware of the
difference between l1-gfns and l2-gfns when nested
virtualization is in use. This fixes a potential
data-corruption problem in the l1-guest and makes the code
work correct (at least as correct as the hardware which is
emulated in this code) again.
Cc: stable@kernel.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
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>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: Flush TLB if PGD entry is changed in i386 PAE mode
x86, dumpstack: Correct stack dump info when frame pointer is available
x86: Clean up csum-copy_64.S a bit
x86: Fix common misspellings
x86: Fix misspelling and align params
x86: Use PentiumPro-optimized partial_csum() on VIA C7
They were generated by 'codespell' and then manually reviewed.
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: trivial@kernel.org
LKML-Reference: <1300389856-1099-3-git-send-email-lucas.demarchi@profusion.mobi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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>
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>
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>
If KVM sees a read-only host page, it will map it as read-only to prevent
breaking a COW. However, if the page was part of a large guest page, KVM
incorrectly extends the write protection to the entire large page frame
instead of limiting it to the normal host page.
This results in the instantiation of a new shadow page with read-only access.
If this happens for a MOVS instruction that moves memory between two normal
pages, within a single large page frame, and mapped within the guest as a
large page, and if, in addition, the source operand is not writeable in the
host (perhaps due to KSM), then KVM will instantiate a read-only direct
shadow page, instantiate an spte for the source operand, then instantiate
a new read/write direct shadow page and instantiate an spte for the
destination operand. Since these two sptes are in different shadow pages,
MOVS will never see them at the same time and the guest will not make
progress.
Fix by mapping the direct shadow page read/write, and only marking the
host page read-only.
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>
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>
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>
Quote from Avi:
| I don't think we need to flush immediately; set a "tlb dirty" bit somewhere
| that is cleareded when we flush the tlb. kvm_mmu_notifier_invalidate_page()
| can consult the bit and force a flush if set.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.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 should flush all tlbs after drop spte on sync_page path since
Quote from Avi:
| sync_page
| drop_spte
| kvm_mmu_notifier_invalidate_page
| kvm_unmap_rmapp
| spte doesn't exist -> no flush
| page is freed
| guest can write into freed page?
KVM-Stable-Tag.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
If reserved bit is set, we need inject the #PF with PFEC.RSVD=1,
but shadow_notrap_nonpresent_pte injects #PF with PFEC.RSVD=0 only
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
As suggested by Andrea, pass r/w error code to gup(), upgrading read fault
to writable if host pte allows it.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
When page is swapped in it is mapped into guest memory only after guest
tries to access it again and generate another fault. To save this fault
we can map it immediately since we know that guest is going to access
the page. Do it only when tdp is enabled for now. Shadow paging case is
more complicated. CR[034] and EFER registers should be switched before
doing mapping and then switched back.
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
If a guest accesses swapped out memory do not swap it in from vcpu thread
context. Schedule work to do swapping and put vcpu into halted state
instead.
Interrupts will still be delivered to the guest and if interrupt will
cause reschedule guest will continue to run another task.
[avi: remove call to get_user_pages_noio(), nacked by Linus; this
makes everything synchrnous again]
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Move access code parsing from caller site to FNAME(walk_addr) function
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
