Instead of sleeping in kvm_vcpu_on_spin, which can cause gigantic
slowdowns of certain workloads, we instead use yield_to to get
another VCPU in the same KVM guest to run sooner.

This seems to give a 10-15% speedup in certain workloads.
Signed-off-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Keep track of which task is running a KVM vcpu.  This helps us
figure out later what task to wake up if we want to boost a
vcpu that got preempted.

Unfortunately there are no guarantees that the same task
always keeps the same vcpu, so we can only track the task
across a single "run" of the vcpu.
Signed-off-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

is_hwpoison_address only checks whether the page table entry is
hwpoisoned, regardless the memory page mapped.  While __get_user_pages
will check both.

QEMU will clear the poisoned page table entry (via unmap/map) to make
it possible to allocate a new memory page for the virtual address
across guest rebooting.  But it is also possible that the underlying
memory page is kept poisoned even after the corresponding page table
entry is cleared, that is, a new memory page can not be allocated.
__get_user_pages can catch these situations.
Signed-off-by: NHuang Ying <ying.huang@intel.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Now, we have 'vcpu->mode' to judge whether need to send ipi to other
cpus, this way is very exact, so checking request bit is needless,
then we can drop the spinlock let it's collateral
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Currently we keep track of only two states: guest mode and host
mode.  This patch adds an "exiting guest mode" state that tells
us that an IPI will happen soon, so unless we need to wait for the
IPI, we can avoid it completely.

Also
1: No need atomically to read/write ->mode in vcpu's thread

2: reorganize struct kvm_vcpu to make ->mode and ->requests
   in the same cache line explicitly
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Get rid of this warning:

  CC      arch/s390/kvm/../../../virt/kvm/kvm_main.o
arch/s390/kvm/../../../virt/kvm/kvm_main.c:596:12: warning: 'kvm_create_dirty_bitmap' defined but not used

The only caller of the function is within a !CONFIG_S390 section, so add the
same ifdef around kvm_create_dirty_bitmap() as well.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Instead, drop large mappings, which were the reason we dropped shadow.
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Cleanup some code with common compound_trans_head helper.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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: NAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus 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: NAndrea Arcangeli <aarcange@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since vmx blocks INIT signals, we disable virtualization extensions during
reboot.  This leads to virtualization instructions faulting; we trap these
faults and spin while the reboot continues.

Unfortunately spinning on a non-preemptible kernel may block a task that
reboot depends on; this causes the reboot to hang.

Fix by skipping over the instruction and hoping for the best.
Signed-off-by: NAvi Kivity <avi@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: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Store irq routing table pointer in the irqfd object,
and use that to inject MSI directly without bouncing out to
a kernel thread.

While we touch this structure, rearrange irqfd fields to make fastpath
better packed for better cache utilization.

This also adds some comments about locking rules and rcu usage in code.

Some notes on the design:
- Use pointer into the rt instead of copying an entry,
  to make it possible to use rcu, thus side-stepping
  locking complexities.  We also save some memory this way.
- Old workqueue code is still used for level irqs.
  I don't think we DTRT with level anyway, however,
  it seems easier to keep the code around as
  it has been thought through and debugged, and fix level later than
  rip out and re-instate it later.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NMarcelo Tosatti <mtosatti@redhat.com>
Acked-by: NGregory Haskins <ghaskins@novell.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The naming convension of hardware_[dis|en]able family is little bit confusing
because only hardware_[dis|en]able_all are using _nolock suffix.

Renaming current hardware_[dis|en]able() to *_nolock() and using
hardware_[dis|en]able() as wrapper functions which take kvm_lock for them
reduces extra confusion.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

In kvm_cpu_hotplug(), only CPU_STARTING case is protected by kvm_lock.
This patch adds missing protection for CPU_DYING case.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Any arch not supporting device assigment will also not build
assigned-dev.c. So testing for KVM_CAP_DEVICE_DEASSIGNMENT is pointless.
KVM_CAP_ASSIGN_DEV_IRQ is unconditinally set. Moreover, add a default
case for dispatching the ioctl.
Acked-by: NAlex Williamson <alex.williamson@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

The guest may change states that pci_reset_function does not touch. So
we better save/restore the assigned device across guest usage.
Acked-by: NAlex Williamson <alex.williamson@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Cosmetic change, but it helps to correlate IRQs with PCI devices.
Acked-by: NAlex Williamson <alex.williamson@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This improves the IRQ forwarding for assigned devices: By using the
kernel's threaded IRQ scheme, we can get rid of the latency-prone work
queue and simplify the code in the same run.

Moreover, we no longer have to hold assigned_dev_lock while raising the
guest IRQ, which can be a lenghty operation as we may have to iterate
over all VCPUs. The lock is now only used for synchronizing masking vs.
unmasking of INTx-type IRQs, thus is renames to intx_lock.
Acked-by: NAlex Williamson <alex.williamson@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

When we deassign a guest IRQ, clear the potentially asserted guest line.
There might be no chance for the guest to do this, specifically if we
switch from INTx to MSI mode.
Acked-by: NAlex Williamson <alex.williamson@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

IA64 support forces us to abstract the allocation of the kvm structure.
But instead of mixing this up with arch-specific initialization and
doing the same on destruction, split both steps. This allows to move
generic destruction calls into generic code.

It also fixes error clean-up on failures of kvm_create_vm for IA64.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

In kvm_async_pf_wakeup_all(), we add a dummy apf to vcpu->async_pf.done
without holding vcpu->async_pf.lock, it will break if we are handling apfs
at this time.

Also use 'list_empty_careful()' instead of 'list_empty()'
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

If it's no need to inject async #PF to PV guest we can handle
more completed apfs at one time, so we can retry guest #PF
as early as possible
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Let's use newly introduced vzalloc().
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Fixes this:

  CC      arch/s390/kvm/../../../virt/kvm/kvm_main.o
arch/s390/kvm/../../../virt/kvm/kvm_main.c: In function 'kvm_dev_ioctl_create_vm':
arch/s390/kvm/../../../virt/kvm/kvm_main.c:1828:10: warning: unused variable 'r'
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Fixes this:

  CC      arch/s390/kvm/../../../virt/kvm/kvm_main.o
arch/s390/kvm/../../../virt/kvm/kvm_main.c: In function 'kvm_clear_guest_page':
arch/s390/kvm/../../../virt/kvm/kvm_main.c:1224:2: warning: passing argument 3 of 'kvm_write_guest_page' makes pointer from integer without a cast
arch/s390/kvm/../../../virt/kvm/kvm_main.c:1185:5: note: expected 'const void *' but argument is of type 'long unsigned int'
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Currently we are using vmalloc() for all dirty bitmaps even if
they are small enough, say less than K bytes.

We use kmalloc() if dirty bitmap size is less than or equal to
PAGE_SIZE so that we can avoid vmalloc area usage for VGA.

This will also make the logging start/stop faster.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Currently x86's kvm_vm_ioctl_get_dirty_log() needs to allocate a bitmap by
vmalloc() which will be used in the next logging and this has been causing
bad effect to VGA and live-migration: vmalloc() consumes extra systime,
triggers tlb flush, etc.

This patch resolves this issue by pre-allocating one more bitmap and switching
between two bitmaps during dirty logging.

Performance improvement:
  I measured performance for the case of VGA update by trace-cmd.
  The result was 1.5 times faster than the original one.

  In the case of live migration, the improvement ratio depends on the workload
  and the guest memory size. In general, the larger the memory size is the more
  benefits we get.

Note:
  This does not change other architectures's logic but the allocation size
  becomes twice. This will increase the actual memory consumption only when
  the new size changes the number of pages allocated by vmalloc().
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NFernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This makes it easy to change the way of allocating/freeing dirty bitmaps.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NFernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Add tracepoint for userspace exit.
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo 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: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Improve vma handling code readability in hva_to_pfn() and fix
async pf handling code to properly check vma returned by find_vma().
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Send async page fault to a PV guest if it accesses swapped out memory.
Guest will choose another task to run upon receiving the fault.

Allow async page fault injection only when guest is in user mode since
otherwise guest may be in non-sleepable context and will not be able
to reschedule.

Vcpu will be halted if guest will fault on the same page again or if
vcpu executes kernel code.
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Guest enables async PF vcpu functionality using this MSR.
Reviewed-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Keep track of memslots changes by keeping generation number in memslots
structure. Provide kvm_write_guest_cached() function that skips
gfn_to_hva() translation if memslots was not changed since previous
invocation.
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@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: NRik van Riel <riel@redhat.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo 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: NRik van Riel <riel@redhat.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

We also have to call kvm_iommu_map_pages for CONFIG_AMD_IOMMU. So drop
the dependency on Intel IOMMU, kvm_iommu_map_pages will be a nop anyway
if CONFIG_IOMMU_API is not defined.

KVM-Stable-Tag.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Fix typo in copyright notice.
Signed-off-by: NNicolas Kaiser <nikai@nikai.net>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>