Avoid the "writable" check in __gfn_to_hva_many(), which will always fail
on read-only memslots due to gfn_to_hva() assuming writes. Functionally,
this allows x86 to create large mappings for read-only memslots that
are backed by HugeTLB mappings.
Note, the changelog for commit 05da45583d ("KVM: MMU: large page
support") states "If the largepage contains write-protected pages, a
large pte is not used.", but "write-protected" refers to pages that are
temporarily read-only, e.g. read-only memslots didn't even exist at the
time.
Fixes: 4d8b81abc4 ("KVM: introduce readonly memslot")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
[Redone using kvm_vcpu_gfn_to_memslot_prot. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use kvm_vcpu_gfn_to_hva() when retrieving the host page size so that the
correct set of memslots is used when handling x86 page faults in SMM.
Fixes: 54bf36aac5 ("KVM: x86: use vcpu-specific functions to read/write/translate GFNs")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a helper, is_transparent_hugepage(), to explicitly check whether a
compound page is a THP and use it when populating KVM's secondary MMU.
The explicit check fixes a bug where a remapped compound page, e.g. for
an XDP Rx socket, is mapped into a KVM guest and is mistaken for a THP,
which results in KVM incorrectly creating a huge page in its secondary
MMU.
Fixes: 936a5fe6e6 ("thp: kvm mmu transparent hugepage support")
Reported-by: syzbot+c9d1fb51ac9d0d10c39d@syzkaller.appspotmail.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Check the result of __kvm_gfn_to_hva_cache_init() and return immediately
instead of relying on the kvm_is_error_hva() check to detect errors so
that it's abundantly clear KVM intends to immediately bail on an error.
Note, the hva check is still mandatory to handle errors on subqeuesnt
calls with the same generation. Similarly, always return -EFAULT on
error so that multiple (bad) calls for a given generation will get the
same result, e.g. on an illegal gfn wrap, propagating the return from
__kvm_gfn_to_hva_cache_init() would cause the initial call to return
-EINVAL and subsequent calls to return -EFAULT.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Barret reported a (technically benign) bug where nr_pages_avail can be
accessed without being initialized if gfn_to_hva_many() fails.
virt/kvm/kvm_main.c:2193:13: warning: 'nr_pages_avail' may be
used uninitialized in this function [-Wmaybe-uninitialized]
Rather than simply squashing the warning by initializing nr_pages_avail,
fix the underlying issues by reworking __kvm_gfn_to_hva_cache_init() to
return immediately instead of continuing on. Now that all callers check
the result and/or bail immediately on a bad hva, there's no need to
explicitly nullify the memslot on error.
Reported-by: Barret Rhoden <brho@google.com>
Fixes: f1b9dd5eb8 ("kvm: Disallow wraparound in kvm_gfn_to_hva_cache_init")
Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When reading/writing using the guest/host cache, check for a bad hva
before checking for a NULL memslot, which triggers the slow path for
handing cross-page accesses. Because the memslot is nullified on error
by __kvm_gfn_to_hva_cache_init(), if the bad hva is encountered after
crossing into a new page, then the kvm_{read,write}_guest() slow path
could potentially write/access the first chunk prior to detecting the
bad hva.
Arguably, performing a partial access is semantically correct from an
architectural perspective, but that behavior is certainly not intended.
In the original implementation, memslot was not explicitly nullified
and therefore the partial access behavior varied based on whether the
memslot itself was null, or if the hva was simply bad. The current
behavior was introduced as a seemingly unintentional side effect in
commit f1b9dd5eb8 ("kvm: Disallow wraparound in
kvm_gfn_to_hva_cache_init"), which justified the change with "since some
callers don't check the return code from this function, it sit seems
prudent to clear ghc->memslot in the event of an error".
Regardless of intent, the partial access is dependent on _not_ checking
the result of the cache initialization, which is arguably a bug in its
own right, at best simply weird.
Fixes: 8f964525a1 ("KVM: Allow cross page reads and writes from cached translations.")
Cc: Jim Mattson <jmattson@google.com>
Cc: Andrew Honig <ahonig@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
For ring-based dirty log tracking, it will be more efficient to account
writes during schedule-out or schedule-in to the currently running VCPU.
We would like to do it even if the write doesn't use the current VCPU's
address space, as is the case for cached writes (see commit 4e335d9e7d,
"Revert "KVM: Support vCPU-based gfn->hva cache"", 2017-05-02).
Therefore, add a mechanism to track the currently-loaded kvm_vcpu struct.
There is already something similar in KVM/ARM; one important difference
is that kvm_arch_vcpu_{load,put} have two callers in virt/kvm/kvm_main.c:
we have to update both the architecture-independent vcpu_{load,put} and
the preempt notifiers.
Another change made in the process is to allow using kvm_get_running_vcpu()
in preemptible code. This is allowed because preempt notifiers ensure
that the value does not change even after the VCPU thread is migrated.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It's already going to reach 2400 Bytes (which is over half of page
size on 4K page archs), so maybe it's good to have this build-time
check in case it overflows when adding new fields.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove kvm_read_guest_atomic() because it's not used anywhere.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Open code the allocation and freeing of the vcpu->run page in
kvm_vm_ioctl_create_vcpu() and kvm_vcpu_destroy() respectively. Doing
so allows kvm_vcpu_init() to be a pure init function and eliminates
kvm_vcpu_uninit() entirely.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move the putting of vcpu->pid to kvm_vcpu_destroy(). vcpu->pid is
guaranteed to be NULL when kvm_vcpu_uninit() is called in the error path
of kvm_vm_ioctl_create_vcpu(), e.g. it is explicitly nullified by
kvm_vcpu_init() and is only changed by KVM_RUN.
No functional change intended.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove kvm_arch_vcpu_init() and kvm_arch_vcpu_uninit() now that all
arch specific implementations are nops.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove kvm_arch_vcpu_setup() now that all arch specific implementations
are nops.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Initialize the preempt notifier immediately in kvm_vcpu_init() to pave
the way for removing kvm_arch_vcpu_setup(), i.e. to allow arch specific
code to call vcpu_load() during kvm_arch_vcpu_create().
Back when preemption support was added, the location of the call to init
the preempt notifier was perfectly sane. The overall vCPU creation flow
featured a single arch specific hook and the preempt notifer was used
immediately after its initialization (by vcpu_load()). E.g.:
vcpu = kvm_arch_ops->vcpu_create(kvm, n);
if (IS_ERR(vcpu))
return PTR_ERR(vcpu);
preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);
vcpu_load(vcpu);
r = kvm_mmu_setup(vcpu);
vcpu_put(vcpu);
if (r < 0)
goto free_vcpu;
Today, the call to preempt_notifier_init() is sandwiched between two
arch specific calls, kvm_arch_vcpu_create() and kvm_arch_vcpu_setup(),
which needlessly forces x86 (and possibly others?) to split its vCPU
creation flow. Init the preempt notifier prior to any arch specific
call so that each arch can independently decide how best to organize
its creation flow.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Unexport kvm_vcpu_cache and kvm_vcpu_{un}init() and make them static
now that they are referenced only in kvm_main.c.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Now that all architectures tightly couple vcpu allocation/free with the
mandatory calls to kvm_{un}init_vcpu(), move the sequences verbatim to
common KVM code.
Move both allocation and initialization in a single patch to eliminate
thrash in arch specific code. The bisection benefits of moving the two
pieces in separate patches is marginal at best, whereas the odds of
introducing a transient arch specific bug are non-zero.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add kvm_vcpu_destroy() and wire up all architectures to call the common
function instead of their arch specific implementation. The common
destruction function will be used by future patches to move allocation
and initialization of vCPUs to common KVM code, i.e. to free resources
that are allocated by arch agnostic code.
No functional change intended.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a pre-allocation arch hook to handle checks that are currently done
by arch specific code prior to allocating the vCPU object. This paves
the way for moving the allocation to common KVM code.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We can store reference to kvm_stats_debugfs_item instead of copying
its values to kvm_stat_data.
This allows us to remove duplicated code and usage of temporary
kvm_stat_data inside vm_stat_get et al.
Signed-off-by: Milan Pandurov <milanpa@amazon.de>
Reviewed-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Fix some wrong function names in comment. mmu_check_roots is a typo for
mmu_check_root, vmcs_read_any should be vmcs12_read_any and so on.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We can get rid of unnecessary var page in
kvm_set_pfn_dirty() , thus make code style
similar with kvm_set_pfn_accessed().
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The jump label out_free_1 and out_free_2 deal with
the same stuff, so git rid of one and rename the
label out_free_0a to retain the label name order.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- Allow non-ISV data aborts to be reported to userspace
- Allow injection of data aborts from userspace
- Expose stolen time to guests
- GICv4 performance improvements
- vgic ITS emulation fixes
- Simplify FWB handling
- Enable halt pool counters
- Make the emulated timer PREEMPT_RT compliant
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Merge tag 'kvmarm-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm updates for Linux 5.5:
- Allow non-ISV data aborts to be reported to userspace
- Allow injection of data aborts from userspace
- Expose stolen time to guests
- GICv4 performance improvements
- vgic ITS emulation fixes
- Simplify FWB handling
- Enable halt pool counters
- Make the emulated timer PREEMPT_RT compliant
Conflicts:
include/uapi/linux/kvm.h
Fetching an index for any vcpu in kvm->vcpus array by traversing
the entire array everytime is costly.
This patch remembers the position of each vcpu in kvm->vcpus array
by storing it in vcpus_idx under kvm_vcpu structure.
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a comment explaining the rational behind having both
no_compat open and ioctl callbacks to fend off compat tasks.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
On a system without KVM_COMPAT, we prevent IOCTLs from being issued
by a compat task. Although this prevents most silly things from
happening, it can still confuse a 32bit userspace that is able
to open the kvm device (the qemu test suite seems to be pretty
mad with this behaviour).
Take a more radical approach and return a -ENODEV to the compat
task.
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
VT-d posted interrupts, DAX/ZONE_DEVICE,
module unload/reload.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm fixes from Paolo Bonzini:
"Fix unwinding of KVM_CREATE_VM failure, VT-d posted interrupts,
DAX/ZONE_DEVICE, and module unload/reload"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved
KVM: VMX: Introduce pi_is_pir_empty() helper
KVM: VMX: Do not change PID.NDST when loading a blocked vCPU
KVM: VMX: Consider PID.PIR to determine if vCPU has pending interrupts
KVM: VMX: Fix comment to specify PID.ON instead of PIR.ON
KVM: X86: Fix initialization of MSR lists
KVM: fix placement of refcount initialization
KVM: Fix NULL-ptr deref after kvm_create_vm fails
Explicitly exempt ZONE_DEVICE pages from kvm_is_reserved_pfn() and
instead manually handle ZONE_DEVICE on a case-by-case basis. For things
like page refcounts, KVM needs to treat ZONE_DEVICE pages like normal
pages, e.g. put pages grabbed via gup(). But for flows such as setting
A/D bits or shifting refcounts for transparent huge pages, KVM needs to
to avoid processing ZONE_DEVICE pages as the flows in question lack the
underlying machinery for proper handling of ZONE_DEVICE pages.
This fixes a hang reported by Adam Borowski[*] in dev_pagemap_cleanup()
when running a KVM guest backed with /dev/dax memory, as KVM straight up
doesn't put any references to ZONE_DEVICE pages acquired by gup().
Note, Dan Williams proposed an alternative solution of doing put_page()
on ZONE_DEVICE pages immediately after gup() in order to simplify the
auditing needed to ensure is_zone_device_page() is called if and only if
the backing device is pinned (via gup()). But that approach would break
kvm_vcpu_{un}map() as KVM requires the page to be pinned from map() 'til
unmap() when accessing guest memory, unlike KVM's secondary MMU, which
coordinates with mmu_notifier invalidations to avoid creating stale
page references, i.e. doesn't rely on pages being pinned.
[*] http://lkml.kernel.org/r/20190919115547.GA17963@angband.pl
Reported-by: Adam Borowski <kilobyte@angband.pl>
Analyzed-by: David Hildenbrand <david@redhat.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: stable@vger.kernel.org
Fixes: 3565fce3a6 ("mm, x86: get_user_pages() for dax mappings")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reported by syzkaller:
=============================
WARNING: suspicious RCU usage
-----------------------------
./include/linux/kvm_host.h:536 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
no locks held by repro_11/12688.
stack backtrace:
Call Trace:
dump_stack+0x7d/0xc5
lockdep_rcu_suspicious+0x123/0x170
kvm_dev_ioctl+0x9a9/0x1260 [kvm]
do_vfs_ioctl+0x1a1/0xfb0
ksys_ioctl+0x6d/0x80
__x64_sys_ioctl+0x73/0xb0
do_syscall_64+0x108/0xaa0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Commit a97b0e773e (kvm: call kvm_arch_destroy_vm if vm creation fails)
sets users_count to 1 before kvm_arch_init_vm(), however, if kvm_arch_init_vm()
fails, we need to decrease this count. By moving it earlier, we can push
the decrease to out_err_no_arch_destroy_vm without introducing yet another
error label.
syzkaller source: https://syzkaller.appspot.com/x/repro.c?x=15209b84e00000
Reported-by: syzbot+75475908cd0910f141ee@syzkaller.appspotmail.com
Fixes: a97b0e773e ("kvm: call kvm_arch_destroy_vm if vm creation fails")
Cc: Jim Mattson <jmattson@google.com>
Analyzed-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reported by syzkaller:
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 14727 Comm: syz-executor.3 Not tainted 5.4.0-rc4+ #0
RIP: 0010:kvm_coalesced_mmio_init+0x5d/0x110 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:121
Call Trace:
kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:3446 [inline]
kvm_dev_ioctl+0x781/0x1490 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3494
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0x196/0x1150 fs/ioctl.c:696
ksys_ioctl+0x62/0x90 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:718
do_syscall_64+0xca/0x5d0 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Commit 9121923c45 ("kvm: Allocate memslots and buses before calling kvm_arch_init_vm")
moves memslots and buses allocations around, however, if kvm->srcu/irq_srcu fails
initialization, NULL will be returned instead of error code, NULL will not be intercepted
in kvm_dev_ioctl_create_vm() and be dereferenced by kvm_coalesced_mmio_init(), this patch
fixes it.
Moving the initialization is required anyway to avoid an incorrect synchronize_srcu that
was also reported by syzkaller:
wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136
__synchronize_srcu+0x197/0x250 kernel/rcu/srcutree.c:921
synchronize_srcu_expedited kernel/rcu/srcutree.c:946 [inline]
synchronize_srcu+0x239/0x3e8 kernel/rcu/srcutree.c:997
kvm_page_track_unregister_notifier+0xe7/0x130 arch/x86/kvm/page_track.c:212
kvm_mmu_uninit_vm+0x1e/0x30 arch/x86/kvm/mmu.c:5828
kvm_arch_destroy_vm+0x4a2/0x5f0 arch/x86/kvm/x86.c:9579
kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:702 [inline]
so do it.
Reported-by: syzbot+89a8060879fa0bd2db4f@syzkaller.appspotmail.com
Reported-by: syzbot+e27e7027eb2b80e44225@syzkaller.appspotmail.com
Fixes: 9121923c45 ("kvm: Allocate memslots and buses before calling kvm_arch_init_vm")
Cc: Jim Mattson <jmattson@google.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The page table pages corresponding to broken down large pages are zapped in
FIFO order, so that the large page can potentially be recovered, if it is
not longer being used for execution. This removes the performance penalty
for walking deeper EPT page tables.
By default, one large page will last about one hour once the guest
reaches a steady state.
Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add a function to create a kernel thread associated with a given VM. In
particular, it ensures that the worker thread inherits the priority and
cgroups of the calling thread.
Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In kvm_create_vm(), if we've successfully called kvm_arch_init_vm(), but
then fail later in the function, we need to call kvm_arch_destroy_vm()
so that it can do any necessary cleanup (like freeing memory).
Fixes: 44a95dae1d ("KVM: x86: Detect and Initialize AVIC support")
Signed-off-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Junaid Shahid <junaids@google.com>
[Remove dependency on "kvm: Don't clear reference count on
kvm_create_vm() error path" which was not committed. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This reorganization will allow us to call kvm_arch_destroy_vm in the
event that kvm_create_vm fails after calling kvm_arch_init_vm.
Suggested-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a new helper, kvm_put_kvm_no_destroy(), to handle putting a borrowed
reference[*] to the VM when installing a new file descriptor fails. KVM
expects the refcount to remain valid in this case, as the in-progress
ioctl() has an explicit reference to the VM. The primary motiviation
for the helper is to document that the 'kvm' pointer is still valid
after putting the borrowed reference, e.g. to document that doing
mutex(&kvm->lock) immediately after putting a ref to kvm isn't broken.
[*] When exposing a new object to userspace via a file descriptor, e.g.
a new vcpu, KVM grabs a reference to itself (the VM) prior to making
the object visible to userspace to avoid prematurely freeing the VM
in the scenario where userspace immediately closes file descriptor.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Don't waste cycles to shrink/grow vCPU halt_poll_ns if host
side polling is disabled.
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently a kvm_device_ops structure cannot be const without triggering
compiler warnings. However the structure doesn't need to be written to
and, by marking it const, it can be read-only in memory. Add some more
const keywords to allow this.
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
The largepages debugfs entry is incremented/decremented as shadow
pages are created or destroyed. Clearing it will result in an
underflow, which is harmless to KVM but ugly (and could be
misinterpreted by tools that use debugfs information), so make
this particular statistic read-only.
Cc: kvm-ppc@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When a vpcu is about to block by calling kvm_vcpu_block, we call
back into the arch code to allow any form of synchronization that
may be required at this point (SVN stops the AVIC, ARM synchronises
the VMCR and enables GICv4 doorbells). But this synchronization
comes in quite late, as we've potentially waited for halt_poll_ns
to expire.
Instead, let's move kvm_arch_vcpu_blocking() to the beginning of
kvm_vcpu_block(), which on ARM has several benefits:
- VMCR gets synchronised early, meaning that any interrupt delivered
during the polling window will be evaluated with the correct guest
PMR
- GICv4 doorbells are enabled, which means that any guest interrupt
directly injected during that window will be immediately recognised
Tang Nianyao ran some tests on a GICv4 machine to evaluate such
change, and reported up to a 10% improvement for netperf:
<quote>
netperf result:
D06 as server, intel 8180 server as client
with change:
package 512 bytes - 5500 Mbits/s
package 64 bytes - 760 Mbits/s
without change:
package 512 bytes - 5000 Mbits/s
package 64 bytes - 710 Mbits/s
</quote>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
The same check is already done in kvm_is_reserved_pfn.
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.
Also, when doing this, change kvm_arch_create_vcpu_debugfs() to return
void instead of an integer, as we should not care at all about if this
function actually does anything or not.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <x86@kernel.org>
Cc: <kvm@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
There is no need for this function as all arches have to implement
kvm_arch_create_vcpu_debugfs() no matter what. A #define symbol
let us actually simplify the code.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
After commit d73eb57b80 (KVM: Boost vCPUs that are delivering interrupts), a
five years old bug is exposed. Running ebizzy benchmark in three 80 vCPUs VMs
on one 80 pCPUs Skylake server, a lot of rcu_sched stall warning splatting
in the VMs after stress testing:
INFO: rcu_sched detected stalls on CPUs/tasks: { 4 41 57 62 77} (detected by 15, t=60004 jiffies, g=899, c=898, q=15073)
Call Trace:
flush_tlb_mm_range+0x68/0x140
tlb_flush_mmu.part.75+0x37/0xe0
tlb_finish_mmu+0x55/0x60
zap_page_range+0x142/0x190
SyS_madvise+0x3cd/0x9c0
system_call_fastpath+0x1c/0x21
swait_active() sustains to be true before finish_swait() is called in
kvm_vcpu_block(), voluntarily preempted vCPUs are taken into account
by kvm_vcpu_on_spin() loop greatly increases the probability condition
kvm_arch_vcpu_runnable(vcpu) is checked and can be true, when APICv
is enabled the yield-candidate vCPU's VMCS RVI field leaks(by
vmx_sync_pir_to_irr()) into spinning-on-a-taken-lock vCPU's current
VMCS.
This patch fixes it by checking conservatively a subset of events.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Marc Zyngier <Marc.Zyngier@arm.com>
Cc: stable@vger.kernel.org
Fixes: 98f4a1467 (KVM: add kvm_arch_vcpu_runnable() test to kvm_vcpu_on_spin() loop)
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
preempted_in_kernel is updated in preempt_notifier when involuntary preemption
ocurrs, it can be stale when the voluntarily preempted vCPUs are taken into
account by kvm_vcpu_on_spin() loop. This patch lets it just check preempted_in_kernel
for involuntary preemption.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Inspired by commit 9cac38dd5d (KVM/s390: Set preempted flag during
vcpu wakeup and interrupt delivery), we want to also boost not just
lock holders but also vCPUs that are delivering interrupts. Most
smp_call_function_many calls are synchronous, so the IPI target vCPUs
are also good yield candidates. This patch introduces vcpu->ready to
boost vCPUs during wakeup and interrupt delivery time; unlike s390 we do
not reuse vcpu->preempted so that voluntarily preempted vCPUs are taken
into account by kvm_vcpu_on_spin, but vmx_vcpu_pi_put is not affected
(VT-d PI handles voluntary preemption separately, in pi_pre_block).
Testing on 80 HT 2 socket Xeon Skylake server, with 80 vCPUs VM 80GB RAM:
ebizzy -M
vanilla boosting improved
1VM 21443 23520 9%
2VM 2800 8000 180%
3VM 1800 3100 72%
Testing on my Haswell desktop 8 HT, with 8 vCPUs VM 8GB RAM, two VMs,
one running ebizzy -M, the other running 'stress --cpu 2':
w/ boosting + w/o pv sched yield(vanilla)
vanilla boosting improved
1570 4000 155%
w/ boosting + w/ pv sched yield(vanilla)
vanilla boosting improved
1844 5157 179%
w/o boosting, perf top in VM:
72.33% [kernel] [k] smp_call_function_many
4.22% [kernel] [k] call_function_i
3.71% [kernel] [k] async_page_fault
w/ boosting, perf top in VM:
38.43% [kernel] [k] smp_call_function_many
6.31% [kernel] [k] async_page_fault
6.13% libc-2.23.so [.] __memcpy_avx_unaligned
4.88% [kernel] [k] call_function_interrupt
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- Add support for chained PMU counters in guests
- Improve SError handling
- Handle Neoverse N1 erratum #1349291
- Allow side-channel mitigation status to be migrated
- Standardise most AArch64 system register accesses to msr_s/mrs_s
- Fix host MPIDR corruption on 32bit
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Merge tag 'kvm-arm-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm updates for 5.3
- Add support for chained PMU counters in guests
- Improve SError handling
- Handle Neoverse N1 erratum #1349291
- Allow side-channel mitigation status to be migrated
- Standardise most AArch64 system register accesses to msr_s/mrs_s
- Fix host MPIDR corruption on 32bit
The field "page" is initialized to KVM_UNMAPPED_PAGE when it is not used
(i.e. when the memory lives outside kernel control). So this check will
always end up using kunmap even for memremap regions.
Fixes: e45adf665a ("KVM: Introduce a new guest mapping API")
Cc: stable@vger.kernel.org
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson