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  5. Sep 23, 2023
    • Paolo Bonzini's avatar
      Merge tag 'kvm-riscv-fixes-6.6-1' of https://github.com/kvm-riscv/linux into HEAD · 5804c19b
      Paolo Bonzini authored 
      KVM/riscv fixes for 6.6, take #1

- Fix KVM_GET_REG_LIST API for ISA_EXT registers
- Fix reading ISA_EXT register of a missing extension
- Fix ISA_EXT register handling in get-reg-list test
- Fix filtering of AIA registers in get-reg-list test
      5804c19b
    • Tom Lendacky's avatar
      KVM: SVM: Do not use user return MSR support for virtualized TSC_AUX · 916e3e5f
      Tom Lendacky authored 
      

When the TSC_AUX MSR is virtualized, the TSC_AUX value is swap type "B"
within the VMSA. This means that the guest value is loaded on VMRUN and
the host value is restored from the host save area on #VMEXIT.

Since the value is restored on #VMEXIT, the KVM user return MSR support
for TSC_AUX can be replaced by populating the host save area with the
current host value of TSC_AUX. And, since TSC_AUX is not changed by Linux
post-boot, the host save area can be set once in svm_hardware_enable().
This eliminates the two WRMSR instructions associated with the user return
MSR support.

Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Message-Id: <d381de38eb0ab6c9c93dda8503b72b72546053d7.1694811272.git.thomas.lendacky@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      916e3e5f
    • Tom Lendacky's avatar
      KVM: SVM: Fix TSC_AUX virtualization setup · e0096d01
      Tom Lendacky authored 
      The checks for virtualizing TSC_AUX occur during the vCPU reset processing
path. However, at the time of initial vCPU reset processing, when the vCPU
is first created, not all of the guest CPUID information has been set. In
this case the RDTSCP and RDPID feature support for the guest is not in
place and so TSC_AUX virtualization is not established.

This continues for each vCPU created for the guest. On the first boot of
an AP, vCPU reset processing is executed as a result of an APIC INIT
event, this time with all of the guest CPUID information set, resulting
in TSC_AUX virtualization being enabled, but only for the APs. The BSP
always sees a TSC_AUX value of 0 which probably went unnoticed because,
at least for Linux, the BSP TSC_AUX value is 0.

Move the TSC_AUX virtualization enablement out of the init_vmcb() path and
into the vcpu_after_set_cpuid() path to allow for proper initialization of
the support after the guest CPUID information has been set.

With the TSC_AUX virtualization support now in the vcpu_set_after_cpuid()
path, the intercepts must be either cleared or set based on the guest
CPUID input.

Fixes: 296d5a17

 ("KVM: SEV-ES: Use V_TSC_AUX if available instead of RDTSC/MSR_TSC_AUX intercepts")
Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Message-Id: <4137fbcb9008951ab5f0befa74a0399d2cce809a.1694811272.git.thomas.lendacky@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      e0096d01
    • Paolo Bonzini's avatar
      KVM: SVM: INTERCEPT_RDTSCP is never intercepted anyway · e8d93d5d
      Paolo Bonzini authored 
      svm_recalc_instruction_intercepts() is always called at least once
before the vCPU is started, so the setting or clearing of the RDTSCP
intercept can be dropped from the TSC_AUX virtualization support.

Extracted from a patch by Tom Lendacky.

Cc: stable@vger.kernel.org
Fixes: 296d5a17

 ("KVM: SEV-ES: Use V_TSC_AUX if available instead of RDTSC/MSR_TSC_AUX intercepts")
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      e8d93d5d
    • Sean Christopherson's avatar
      KVM: x86/mmu: Stop zapping invalidated TDP MMU roots asynchronously · 0df9dab8
      Sean Christopherson authored 
      

Stop zapping invalidate TDP MMU roots via work queue now that KVM
preserves TDP MMU roots until they are explicitly invalidated.  Zapping
roots asynchronously was effectively a workaround to avoid stalling a vCPU
for an extended during if a vCPU unloaded a root, which at the time
happened whenever the guest toggled CR0.WP (a frequent operation for some
guest kernels).

While a clever hack, zapping roots via an unbound worker had subtle,
unintended consequences on host scheduling, especially when zapping
multiple roots, e.g. as part of a memslot.  Because the work of zapping a
root is no longer bound to the task that initiated the zap, things like
the CPU affinity and priority of the original task get lost.  Losing the
affinity and priority can be especially problematic if unbound workqueues
aren't affined to a small number of CPUs, as zapping multiple roots can
cause KVM to heavily utilize the majority of CPUs in the system, *beyond*
the CPUs KVM is already using to run vCPUs.

When deleting a memslot via KVM_SET_USER_MEMORY_REGION, the async root
zap can result in KVM occupying all logical CPUs for ~8ms, and result in
high priority tasks not being scheduled in in a timely manner.  In v5.15,
which doesn't preserve unloaded roots, the issues were even more noticeable
as KVM would zap roots more frequently and could occupy all CPUs for 50ms+.

Consuming all CPUs for an extended duration can lead to significant jitter
throughout the system, e.g. on ChromeOS with virtio-gpu, deleting memslots
is a semi-frequent operation as memslots are deleted and recreated with
different host virtual addresses to react to host GPU drivers allocating
and freeing GPU blobs.  On ChromeOS, the jitter manifests as audio blips
during games due to the audio server's tasks not getting scheduled in
promptly, despite the tasks having a high realtime priority.

Deleting memslots isn't exactly a fast path and should be avoided when
possible, and ChromeOS is working towards utilizing MAP_FIXED to avoid the
memslot shenanigans, but KVM is squarely in the wrong.  Not to mention
that removing the async zapping eliminates a non-trivial amount of
complexity.

Note, one of the subtle behaviors hidden behind the async zapping is that
KVM would zap invalidated roots only once (ignoring partial zaps from
things like mmu_notifier events).  Preserve this behavior by adding a flag
to identify roots that are scheduled to be zapped versus roots that have
already been zapped but not yet freed.

Add a comment calling out why kvm_tdp_mmu_invalidate_all_roots() can
encounter invalid roots, as it's not at all obvious why zapping
invalidated roots shouldn't simply zap all invalid roots.

Reported-by: default avatarPattara Teerapong <pteerapong@google.com>
Cc: David Stevens <stevensd@google.com>
Cc: Yiwei Zhang<zzyiwei@google.com>
Cc: Paul Hsia <paulhsia@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20230916003916.2545000-4-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      0df9dab8
    • Paolo Bonzini's avatar
      KVM: x86/mmu: Do not filter address spaces in for_each_tdp_mmu_root_yield_safe() · 441a5dfc
      Paolo Bonzini authored 
      

All callers except the MMU notifier want to process all address spaces.
Remove the address space ID argument of for_each_tdp_mmu_root_yield_safe()
and switch the MMU notifier to use __for_each_tdp_mmu_root_yield_safe().

Extracted out of a patch by Sean Christopherson <seanjc@google.com>

Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      441a5dfc
    • Linus Torvalds's avatar
      Merge tag 'hardening-v6.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux · d90b0276
      Linus Torvalds authored 
      Pull hardening fixes from Kees Cook:

 - Fix UAPI stddef.h to avoid C++-ism (Alexey Dobriyan)

 - Fix harmless UAPI stddef.h header guard endif (Alexey Dobriyan)

* tag 'hardening-v6.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  uapi: stddef.h: Fix __DECLARE_FLEX_ARRAY for C++
  uapi: stddef.h: Fix header guard location
      d90b0276
    • Linus Torvalds's avatar
      Merge tag 'xfs-6.6-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux · 3abc79dc
      Linus Torvalds authored 
      Pull xfs fixes from Chandan Babu:

 - Fix an integer overflow bug when processing an fsmap call

 - Fix crash due to CPU hot remove event racing with filesystem mount
   operation

 - During read-only mount, XFS does not allow the contents of the log to
   be recovered when there are one or more unrecognized rcompat features
   in the primary superblock, since the log might have intent items
   which the kernel does not know how to process

 - During recovery of log intent items, XFS now reserves log space
   sufficient for one cycle of a permanent transaction to execute.
   Otherwise, this could lead to livelocks due to non-availability of
   log space

 - On an fs which has an ondisk unlinked inode list, trying to delete a
   file or allocating an O_TMPFILE file can cause the fs to the shutdown
   if the first inode in the ondisk inode list is not present in the
   inode cache. The bug is solved by explicitly loading the first inode
   in the ondisk unlinked inode list into the inode cache if it is not
   already cached

   A similar problem arises when the uncached inode is present in the
   middle of the ondisk unlinked inode list. This second bug is
   triggered when executing operations like quotacheck and bulkstat. In
   this case, XFS now reads in the entire ondisk unlinked inode list

 - Enable LARP mode only on recent v5 filesystems

 - Fix a out of bounds memory access in scrub

 - Fix a performance bug when locating the tail of the log during
   mounting a filesystem

* tag 'xfs-6.6-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: use roundup_pow_of_two instead of ffs during xlog_find_tail
  xfs: only call xchk_stats_merge after validating scrub inputs
  xfs: require a relatively recent V5 filesystem for LARP mode
  xfs: make inode unlinked bucket recovery work with quotacheck
  xfs: load uncached unlinked inodes into memory on demand
  xfs: reserve less log space when recovering log intent items
  xfs: fix log recovery when unknown rocompat bits are set
  xfs: reload entire unlinked bucket lists
  xfs: allow inode inactivation during a ro mount log recovery
  xfs: use i_prev_unlinked to distinguish inodes that are not on the unlinked list
  xfs: remove CPU hotplug infrastructure
  xfs: remove the all-mounts list
  xfs: use per-mount cpumask to track nonempty percpu inodegc lists
  xfs: fix an agbno overflow in __xfs_getfsmap_datadev
  xfs: fix per-cpu CIL structure aggregation racing with dying cpus
  xfs: fix select in config XFS_ONLINE_SCRUB_STATS
      3abc79dc