KVM: MMU: fix page dirty tracking lost while sync page
In sync-page path, if spte.writable is changed, it will lose page dirty
tracking, for example:
assume spte.writable = 0 in a unsync-page, when it's synced, it map spte
to writable(that is spte.writable = 1), later guest write spte.gfn, it means
spte.gfn is dirty, then guest changed this mapping to read-only, after it's
synced, spte.writable = 0
So, when host release the spte, it detect spte.writable = 0 and not mark page
dirty
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Andrea Arcangeli [Fri, 16 Jul 2010 09:52:55 +0000 (11:52 +0200)]
KVM: MMU: fix mmu notifier invalidate handler for huge spte
The index wasn't calculated correctly (off by one) for huge spte so KVM guest
was unstable with transparent hugepages.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
If the destination is a memory operand and the memory cannot
map to a valid page, the xchg instruction emulation and locked
instruction will not work on io regions and stuck in endless
loop. We should emulate exchange as write to fix it.
If pit delivers interrupt while pic is masking it OS will never do EOI
and ack notifier will not be called so when pit will be unmasked no pit
interrupts will be delivered any more. Calling mask notifiers solves this
issue.
Avi Kivity [Tue, 13 Jul 2010 11:27:09 +0000 (14:27 +0300)]
KVM: MMU: Simplify spte fetch() function
Partition the function into three sections:
- fetching indirect shadow pages (host_level > guest_level)
- fetching direct shadow pages (page_level < host_level <= guest_level)
- the final spte (page_level == host_level)
Instead of the current spaghetti.
A slight change from the original code is that we call validate_direct_spte()
more often: previously we called it only for gw->level, now we also call it for
lower levels. The change should have no effect.
[xiao: fix regression caused by validate_direct_spte() called too late]
KVM: Convert mask notifiers to use irqchip/pin instead of gsi
Devices register mask notifier using gsi, but irqchip knows about
irqchip/pin, so conversion from irqchip/pin to gsi should be done before
looking for mask notifier to call.
KVM: Reenter guest after emulation failure if due to access to non-mmio address
When shadow pages are in use sometimes KVM try to emulate an instruction
when it accesses a shadowed page. If emulation fails KVM un-shadows the
page and reenter guest to allow vcpu to execute the instruction. If page
is not in shadow page hash KVM assumes that this was attempt to do MMIO
and reports emulation failure to userspace since there is no way to fix
the situation. This logic has a race though. If two vcpus tries to write
to the same shadowed page simultaneously both will enter emulator, but
only one of them will find the page in shadow page hash since the one who
founds it also removes it from there, so another cpu will report failure
to userspace and will abort the guest.
Fix this by checking (in addition to checking shadowed page hash) that
page that caused the emulation belongs to valid memory slot. If it is
then reenter the guest to allow vcpu to reexecute the instruction.
Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
KVM: Return EFAULT from kvm ioctl when guest accesses bad area
Currently if guest access address that belongs to memory slot but is not
backed up by page or page is read only KVM treats it like MMIO access.
Remove that capability. It was never part of the interface and should
not be relied upon.
Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Avi Kivity [Sun, 6 Jun 2010 12:46:44 +0000 (15:46 +0300)]
KVM: MMU: Don't drop accessed bit while updating an spte
__set_spte() will happily replace an spte with the accessed bit set with
one that has the accessed bit clear. Add a helper update_spte() which checks
for this condition and updates the page flag if needed.
Avi Kivity [Sun, 6 Jun 2010 11:48:06 +0000 (14:48 +0300)]
KVM: MMU: Atomically check for accessed bit when dropping an spte
Currently, in the window between the check for the accessed bit, and actually
dropping the spte, a vcpu can access the page through the spte and set the bit,
which will be ignored by the mmu.
Fix by using an exchange operation to atmoically fetch the spte and drop it.
Avi Kivity [Sun, 6 Jun 2010 11:31:27 +0000 (14:31 +0300)]
KVM: MMU: Introduce drop_spte()
When we call rmap_remove(), we (almost) always immediately follow it by
an __set_spte() to a nonpresent pte. Since we need to perform the two
operations atomically, to avoid losing the dirty and accessed bits, introduce
a helper drop_spte() and convert all call sites.
Commit 341d9b535b6c simplify reload logic while entry guest mode, it
can avoid unnecessary sync-root if KVM_REQ_MMU_RELOAD and
KVM_REQ_MMU_SYNC both set.
But, it cause a issue that when we handle 'KVM_REQ_TLB_FLUSH', the
root is invalid, it is triggered during my test:
Kernel BUG at ffffffffa00212b8 [verbose debug info unavailable]
......
Fixed by directly return if the root is not ready.
For 32bit machines where the physical address width is
larger than the virtual address width the frame number types
in KVM may overflow. Fix this by changing them to u64.
This patch converts unnecessary divide and modulo operations
in the KVM large page related code into logical operations.
This allows to convert gfn_t to u64 while not breaking 32
bit builds.
Alexander Graf [Wed, 30 Jun 2010 13:18:46 +0000 (15:18 +0200)]
KVM: PPC: Make use of hash based Shadow MMU
We just introduced generic functions to handle shadow pages on PPC.
This patch makes the respective backends make use of them, getting
rid of a lot of duplicate code along the way.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Alexander Graf [Wed, 30 Jun 2010 13:18:45 +0000 (15:18 +0200)]
KVM: PPC: Add generic hpte management functions
Currently the shadow paging code keeps an array of entries it knows about.
Whenever the guest invalidates an entry, we loop through that entry,
trying to invalidate matching parts.
While this is a really simple implementation, it is probably the most
ineffective one possible. So instead, let's keep an array of lists around
that are indexed by a hash. This way each PTE can be added by 4 list_add,
removed by 4 list_del invocations and the search only needs to loop through
entries that share the same hash.
This patch implements said lookup and exports generic functions that both
the 32-bit and 64-bit backend can use.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Xiao Guangrong [Wed, 30 Jun 2010 08:03:28 +0000 (16:03 +0800)]
KVM: MMU: fix direct sp's access corrupted
If the mapping is writable but the dirty flag is not set, we will find
the read-only direct sp and setup the mapping, then if the write #PF
occur, we will mark this mapping writable in the read-only direct sp,
now, other real read-only mapping will happily write it without #PF.
It may hurt guest's COW
Fixed by re-install the mapping when write #PF occur.
Xiao Guangrong [Wed, 30 Jun 2010 08:02:45 +0000 (16:02 +0800)]
KVM: MMU: fix conflict access permissions in direct sp
In no-direct mapping, we mark sp is 'direct' when we mapping the
guest's larger page, but its access is encoded form upper page-struct
entire not include the last mapping, it will cause access conflict.
For example, have this mapping:
[W]
/ PDE1 -> |---|
P[W] | | LPA
\ PDE2 -> |---|
[R]
P have two children, PDE1 and PDE2, both PDE1 and PDE2 mapping the
same lage page(LPA). The P's access is WR, PDE1's access is WR,
PDE2's access is RO(just consider read-write permissions here)
When guest access PDE1, we will create a direct sp for LPA, the sp's
access is from P, is W, then we will mark the ptes is W in this sp.
Then, guest access PDE2, we will find LPA's shadow page, is the same as
PDE's, and mark the ptes is RO.
So, if guest access PDE1, the incorrect #PF is occured.
Fixed by encode the last mapping access into direct shadow page
Xiao Guangrong [Wed, 30 Jun 2010 08:02:02 +0000 (16:02 +0800)]
KVM: MMU: fix writable sync sp mapping
While we sync many unsync sp at one time(in mmu_sync_children()),
we may mapping the spte writable, it's dangerous, if one unsync
sp's mapping gfn is another unsync page's gfn.
For example:
SP1.pte[0] = P
SP2.gfn's pfn = P
[SP1.pte[0] = SP2.gfn's pfn]
First, we write protected SP1 and SP2, but SP1 and SP2 are still the
unsync sp.
Then, sync SP1 first, it will detect SP1.pte[0].gfn only has one unsync-sp,
that is SP2, so it will mapping it writable, but we plan to sync SP2 soon,
at this point, the SP2->unsync is not reliable since later we sync SP2 but
SP2->gfn is already writable.
So the final result is: SP2 is the sync page but SP2.gfn is writable.
This bug will corrupt guest's page table, fixed by mark read-only mapping
if the mapped gfn has shadow pages.
Sheng Yang [Wed, 30 Jun 2010 04:25:15 +0000 (12:25 +0800)]
KVM: VMX: Execute WBINVD to keep data consistency with assigned devices
Some guest device driver may leverage the "Non-Snoop" I/O, and explicitly
WBINVD or CLFLUSH to a RAM space. Since migration may occur before WBINVD or
CLFLUSH, we need to maintain data consistency either by:
1: flushing cache (wbinvd) when the guest is scheduled out if there is no
wbinvd exit, or
2: execute wbinvd on all dirty physical CPUs when guest wbinvd exits.
Chris Lalancette [Mon, 21 Jun 2010 15:29:40 +0000 (11:29 -0400)]
KVM: Search the LAPIC's for one that will accept a PIC interrupt
Older versions of 32-bit linux have a "Checking 'hlt' instruction"
test where they repeatedly call the 'hlt' instruction, and then
expect a timer interrupt to kick the CPU out of halt. This happens
before any LAPIC or IOAPIC setup happens, which means that all of
the APIC's are in virtual wire mode at this point. Unfortunately,
the current implementation of virtual wire mode is hardcoded to
only kick the BSP, so if a crash+kexec occurs on a different
vcpu, it will never get kicked.
This patch makes pic_unlock() do the equivalent of
kvm_irq_delivery_to_apic() for the IOAPIC code. That is, it runs
through all of the vcpus looking for one that is in virtual wire
mode. In the normal case where LAPICs and IOAPICs are configured,
this won't be used at all. In the bootstrap phase of a modern
OS, before the LAPICs and IOAPICs are configured, this will have
exactly the same behavior as today; VCPU0 is always looked at
first, so it will always get out of the loop after the first
iteration. This will only go through the loop more than once
during a kexec/kdump, in which case it will only do it a few times
until the kexec'ed kernel programs the LAPIC and IOAPIC.
Signed-off-by: Chris Lalancette <clalance@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Takuya Yoshikawa [Wed, 23 Jun 2010 06:00:29 +0000 (15:00 +0900)]
KVM: ia64: cleanup kvm_ia64_sync_dirty_log()
kvm_ia64_sync_dirty_log() is a helper function for kvm_vm_ioctl_get_dirty_log()
which copies ia64's arch specific dirty bitmap to general one in memslot.
So doing sanity checks in this function is unnatural. We move these checks
outside of this and change the prototype appropriately.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Mon, 21 Jun 2010 13:24:55 +0000 (15:24 +0200)]
KVM: PPC: Make BAT only guest segments work
When a guest sets its SR entry to invalid, we may still find a
corresponding entry in a BAT. So we need to make sure we're not
faulting on invalid SR entries, but instead just claim them to be
BAT resolved.
This resolves breakage experienced when using libogc based guests.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Huang Ying [Tue, 22 Jun 2010 06:23:11 +0000 (14:23 +0800)]
KVM: Fix a race condition for usage of is_hwpoison_address()
is_hwpoison_address accesses the page table, so the caller must hold
current->mm->mmap_sem in read mode. So fix its usage in hva_to_pfn of
kvm accordingly.
Comment is_hwpoison_address to remind other users.
Reported-by: Avi Kivity <avi@redhat.com> Signed-off-by: Huang Ying <ying.huang@intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Sheng Yang [Tue, 22 Jun 2010 05:49:21 +0000 (13:49 +0800)]
KVM: x86: Enable AVX for guest
Enable Intel(R) Advanced Vector Extension(AVX) for guest.
The detection of AVX feature includes OSXSAVE bit testing. When OSXSAVE bit is
not set, even if AVX is supported, the AVX instruction would result in UD as
well. So we're safe to expose AVX bits to guest directly.
Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Avi Kivity [Mon, 21 Jun 2010 07:57:45 +0000 (10:57 +0300)]
KVM: Prevent internal slots from being COWed
If a process with a memory slot is COWed, the page will change its address
(despite having an elevated reference count). This breaks internal memory
slots which have their physical addresses loaded into vmcs registers (see
the APIC access memory slot).
Newer (guest) kernels use sigp sense running in their spinlock
implementation to check if the other cpu is running before yielding
the processor. This revealed some wrong guest settings, causing
unnecessary exits for every sigp sense running.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Wei Yongjun [Thu, 17 Jun 2010 09:33:55 +0000 (17:33 +0800)]
KVM: x86 emulator: fix group3 instruction decoding
Group 3 instruction with ModRM reg field as 001 is
defined as test instruction under AMD arch, and
emulate_grp3() is ready for emulate it, so fix the
decoding.
static inline int emulate_grp3(...)
{
...
switch (c->modrm_reg) {
case 0 ... 1: /* test */
emulate_2op_SrcV("test", c->src, c->dst, ctxt->eflags);
...
}
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Asias He [Sat, 19 Jun 2010 08:52:12 +0000 (16:52 +0800)]
KVM: PPC: fix uninitialized variable warning in kvm_ppc_core_deliver_interrupts
Fixes:
arch/powerpc/kvm/booke.c: In function 'kvmppc_core_deliver_interrupts':
arch/powerpc/kvm/booke.c:147: warning: 'msr_mask' may be used uninitialized in this function
Signed-off-by: Asias He <asias.hejun@gmail.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Chris Lalancette [Wed, 16 Jun 2010 21:11:11 +0000 (17:11 -0400)]
KVM: x86: Introduce a workqueue to deliver PIT timer interrupts
We really want to "kvm_set_irq" during the hrtimer callback,
but that is risky because that is during interrupt context.
Instead, offload the work to a workqueue, which is a bit safer
and should provide most of the same functionality.
Signed-off-by: Chris Lalancette <clalance@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Xiao Guangrong [Fri, 11 Jun 2010 13:35:15 +0000 (21:35 +0800)]
KVM: MMU: don't walk every parent pages while mark unsync
While we mark the parent's unsync_child_bitmap, if the parent is already
unsynced, it no need walk it's parent, it can reduce some unnecessary
workload
Xiao Guangrong [Fri, 11 Jun 2010 13:34:04 +0000 (21:34 +0800)]
KVM: MMU: clear unsync_child_bitmap completely
In current code, some page's unsync_child_bitmap is not cleared completely
in mmu_sync_children(), for example, if two PDPEs shard one PDT, one of
PDPE's unsync_child_bitmap is not cleared.
Currently, it not harm anything just little overload, but it's the prepare
work for the later patch
Denis Kirjanov [Fri, 11 Jun 2010 11:23:26 +0000 (11:23 +0000)]
KVM: PPC: fix build warning in kvm_arch_vcpu_ioctl_run
Fix compile warning:
CC [M] arch/powerpc/kvm/powerpc.o
arch/powerpc/kvm/powerpc.c: In function 'kvm_arch_vcpu_ioctl_run':
arch/powerpc/kvm/powerpc.c:290: warning: 'gpr' may be used uninitialized in this function
arch/powerpc/kvm/powerpc.c:290: note: 'gpr' was declared here
Xiao Guangrong [Tue, 8 Jun 2010 12:07:01 +0000 (20:07 +0800)]
KVM: MMU: delay local tlb flush
delay local tlb flush until enter guest moden, it can reduce vpid flush
frequency and reduce remote tlb flush IPI(if KVM_REQ_TLB_FLUSH bit is
already set, IPI is not sent)
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> Signed-off-by: Avi Kivity <avi@redhat.com>
git://bbs.cooldavid.org / net-next-2.6.git / log