delta/linux.git/include/linux/kvm_host.h, branch proc-cmdline

KVM: Extend MAX_IRQ_ROUTES to 4096 for all archs

2018-05-11T09:21:10+00:00

Our virtual machines make use of device assignment by configuring
12 NVMe disks for high I/O performance. Each NVMe device has 129
MSI-X Table entries:
Capabilities: [50] MSI-X: Enable+ Count=129 Masked-Vector table: BAR=0 offset=00002000
The windows virtual machines fail to boot since they will map the number of
MSI-table entries that the NVMe hardware reported to the bus to msi routing
table, this will exceed the 1024. This patch extends MAX_IRQ_ROUTES to 4096
for all archs, in the future this might be extended again if needed.

Reviewed-by: Cornelia Huck 
Cc: Paolo Bonzini 
Cc: Radim KrÄmÃ¡Å™ 
Cc: Cornelia Huck 
Cc: Christian Borntraeger 
Signed-off-by: Wanpeng Li 
Signed-off-by: Tonny Lu 
Signed-off-by: Paolo Bonzini

kvm: fix warning for non-x86 builds

2018-02-24T00:43:47+00:00

Fix the following sparse warning by moving the prototype
of kvm_arch_mmu_notifier_invalidate_range() to linux/kvm_host.h .

  CHECK   arch/s390/kvm/../../../virt/kvm/kvm_main.c
arch/s390/kvm/../../../virt/kvm/kvm_main.c:138:13: warning: symbol 'kvm_arch_mmu_notifier_invalidate_range' was not declared. Should it be static?

Signed-off-by: Sebastian Ott 
Signed-off-by: Paolo Bonzini

kvm: fix warning for CONFIG_HAVE_KVM_EVENTFD builds

2018-02-24T00:43:46+00:00

Move the kvm_arch_irq_routing_update() prototype outside of
ifdef CONFIG_HAVE_KVM_EVENTFD guards to fix the following sparse warning:

arch/s390/kvm/../../../virt/kvm/irqchip.c:171:28: warning: symbol 'kvm_arch_irq_routing_update' was not declared. Should it be static?

Signed-off-by: Sebastian Ott 
Acked-by: Christian Borntraeger 
Signed-off-by: Paolo Bonzini

KVM: introduce kvm_arch_vcpu_async_ioctl

2017-12-14T08:26:59+00:00

After the vcpu_load/vcpu_put pushdown, the handling of asynchronous VCPU
ioctl is already much clearer in that it is obvious that they bypass
vcpu_load and vcpu_put.

However, it is still not perfect in that the different state of the VCPU
mutex is still hidden in the caller.  Separate those ioctls into a new
function kvm_arch_vcpu_async_ioctl that returns -ENOIOCTLCMD for more
"traditional" synchronous ioctls.

Cc: James Hogan 
Cc: Paul Mackerras 
Cc: Christian Borntraeger 
Reviewed-by: Christoffer Dall 
Reviewed-by: Cornelia Huck 
Suggested-by: Cornelia Huck 
Signed-off-by: Paolo Bonzini

KVM: Take vcpu->mutex outside vcpu_load

2017-12-14T08:26:49+00:00

As we're about to call vcpu_load() from architecture-specific
implementations of the KVM vcpu ioctls, but yet we access data
structures protected by the vcpu->mutex in the generic code, factor
this logic out from vcpu_load().

x86 is the only architecture which calls vcpu_load() outside of the main
vcpu ioctl function, and these calls will no longer take the vcpu mutex
following this patch.  However, with the exception of
kvm_arch_vcpu_postcreate (see below), the callers are either in the
creation or destruction path of the VCPU, which means there cannot be
any concurrent access to the data structure, because the file descriptor
is not yet accessible, or is already gone.

kvm_arch_vcpu_postcreate makes the newly created vcpu potentially
accessible by other in-kernel threads through the kvm->vcpus array, and
we therefore take the vcpu mutex in this case directly.

Signed-off-by: Christoffer Dall 
Reviewed-by: Cornelia Huck 
Signed-off-by: Paolo Bonzini

x86,kvm: move qemu/guest FPU switching out to vcpu_run

2017-12-05T20:16:43+00:00

Currently, every time a VCPU is scheduled out, the host kernel will
first save the guest FPU/xstate context, then load the qemu userspace
FPU context, only to then immediately save the qemu userspace FPU
context back to memory. When scheduling in a VCPU, the same extraneous
FPU loads and saves are done.

This could be avoided by moving from a model where the guest FPU is
loaded and stored with preemption disabled, to a model where the
qemu userspace FPU is swapped out for the guest FPU context for
the duration of the KVM_RUN ioctl.

This is done under the VCPU mutex, which is also taken when other
tasks inspect the VCPU FPU context, so the code should already be
safe for this change. That should come as no surprise, given that
s390 already has this optimization.

This can fix a bug where KVM calls get_user_pages while owning the
FPU, and the file system ends up requesting the FPU again:

    [258270.527947]  __warn+0xcb/0xf0
    [258270.527948]  warn_slowpath_null+0x1d/0x20
    [258270.527951]  kernel_fpu_disable+0x3f/0x50
    [258270.527953]  __kernel_fpu_begin+0x49/0x100
    [258270.527955]  kernel_fpu_begin+0xe/0x10
    [258270.527958]  crc32c_pcl_intel_update+0x84/0xb0
    [258270.527961]  crypto_shash_update+0x3f/0x110
    [258270.527968]  crc32c+0x63/0x8a [libcrc32c]
    [258270.527975]  dm_bm_checksum+0x1b/0x20 [dm_persistent_data]
    [258270.527978]  node_prepare_for_write+0x44/0x70 [dm_persistent_data]
    [258270.527985]  dm_block_manager_write_callback+0x41/0x50 [dm_persistent_data]
    [258270.527988]  submit_io+0x170/0x1b0 [dm_bufio]
    [258270.527992]  __write_dirty_buffer+0x89/0x90 [dm_bufio]
    [258270.527994]  __make_buffer_clean+0x4f/0x80 [dm_bufio]
    [258270.527996]  __try_evict_buffer+0x42/0x60 [dm_bufio]
    [258270.527998]  dm_bufio_shrink_scan+0xc0/0x130 [dm_bufio]
    [258270.528002]  shrink_slab.part.40+0x1f5/0x420
    [258270.528004]  shrink_node+0x22c/0x320
    [258270.528006]  do_try_to_free_pages+0xf5/0x330
    [258270.528008]  try_to_free_pages+0xe9/0x190
    [258270.528009]  __alloc_pages_slowpath+0x40f/0xba0
    [258270.528011]  __alloc_pages_nodemask+0x209/0x260
    [258270.528014]  alloc_pages_vma+0x1f1/0x250
    [258270.528017]  do_huge_pmd_anonymous_page+0x123/0x660
    [258270.528021]  handle_mm_fault+0xfd3/0x1330
    [258270.528025]  __get_user_pages+0x113/0x640
    [258270.528027]  get_user_pages+0x4f/0x60
    [258270.528063]  __gfn_to_pfn_memslot+0x120/0x3f0 [kvm]
    [258270.528108]  try_async_pf+0x66/0x230 [kvm]
    [258270.528135]  tdp_page_fault+0x130/0x280 [kvm]
    [258270.528149]  kvm_mmu_page_fault+0x60/0x120 [kvm]
    [258270.528158]  handle_ept_violation+0x91/0x170 [kvm_intel]
    [258270.528162]  vmx_handle_exit+0x1ca/0x1400 [kvm_intel]

No performance changes were detected in quick ping-pong tests on
my 4 socket system, which is expected since an FPU+xstate load is
on the order of 0.1us, while ping-ponging between CPUs is on the
order of 20us, and somewhat noisy.

Cc: stable@vger.kernel.org
Signed-off-by: Rik van Riel 
Suggested-by: Christian Borntraeger 
Signed-off-by: Paolo Bonzini 
[Fixed a bug where reset_vcpu called put_fpu without preceding load_fpu,
 which happened inside from KVM_CREATE_VCPU ioctl. - Radim]
Signed-off-by: Radim Krčmář

KVM: Let KVM_SET_SIGNAL_MASK work as advertised

2017-11-27T16:53:47+00:00

KVM API says for the signal mask you set via KVM_SET_SIGNAL_MASK, that
"any unblocked signal received [...] will cause KVM_RUN to return with
-EINTR" and that "the signal will only be delivered if not blocked by
the original signal mask".

This, however, is only true, when the calling task has a signal handler
registered for a signal. If not, signal evaluation is short-circuited for
SIG_IGN and SIG_DFL, and the signal is either ignored without KVM_RUN
returning or the whole process is terminated.

Make KVM_SET_SIGNAL_MASK behave as advertised by utilizing logic similar
to that in do_sigtimedwait() to avoid short-circuiting of signals.

Signed-off-by: Jan H. SchÃ¶nherr 
Signed-off-by: Paolo Bonzini

KVM: s390: vsie: use common code functions for pinning

2017-11-09T08:49:47+00:00

We will not see -ENOMEM (gfn_to_hva() will return KVM_ERR_PTR_BAD_PAGE
for all errors). So we can also get rid of special handling in the
callers of pin_guest_page() and always assume that it is a g2 error.

As also kvm_s390_inject_program_int() should never fail, we can
simplify pin_scb(), too.

Signed-off-by: David Hildenbrand 
Message-Id: <20170901151143.22714-1-david@redhat.com>
Acked-by: Cornelia Huck 
Signed-off-by: Christian Borntraeger

KVM: add spinlock optimization framework

2017-08-08T08:57:43+00:00

If a vcpu exits due to request a user mode spinlock, then
the spinlock-holder may be preempted in user mode or kernel mode.
(Note that not all architectures trap spin loops in user mode,
only AMD x86 and ARM/ARM64 currently do).

But if a vcpu exits in kernel mode, then the holder must be
preempted in kernel mode, so we should choose a vcpu in kernel mode
as a more likely candidate for the lock holder.

This introduces kvm_arch_vcpu_in_kernel() to decide whether the
vcpu is in kernel-mode when it's preempted.  kvm_vcpu_on_spin's
new argument says the same of the spinning VCPU.

Signed-off-by: Longpeng(Mike) 
Signed-off-by: Paolo Bonzini

KVM: nVMX: get rid of nested_get_page()

2017-08-07T13:27:00+00:00

nested_get_page() just sounds confusing. All we want is a page from G1.
This is even unrelated to nested.

Let's introduce kvm_vcpu_gpa_to_page() so we don't get too lengthy
lines.

Reviewed-by: Paolo Bonzini 
Signed-off-by: David Hildenbrand 
Signed-off-by: Radim Krčmář 
[Squash pasto fix from Wanpeng Li. - Paolo]
Signed-off-by: Paolo Bonzini