linux.git/include/linux/kvm_host.h, branch v5.15-rc2

Merge tag 'kvmarm-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

2021-09-06T10:34:48+00:00

KVM/arm64 updates for 5.15

- Page ownership tracking between host EL1 and EL2

- Rely on userspace page tables to create large stage-2 mappings

- Fix incompatibility between pKVM and kmemleak

- Fix the PMU reset state, and improve the performance of the virtual PMU

- Move over to the generic KVM entry code

- Address PSCI reset issues w.r.t. save/restore

- Preliminary rework for the upcoming pKVM fixed feature

- A bunch of MM cleanups

- a vGIC fix for timer spurious interrupts

- Various cleanups

KVM: stats: Add VM stat for remote tlb flush requests

2021-09-06T10:30:45+00:00

Add a new stat that counts the number of times a remote TLB flush is
requested, regardless of whether it kicks vCPUs out of guest mode. This
allows us to look at how often flushes are initiated.

Unlike remote_tlb_flush, this one applies to ARM's instruction-set-based
TLB flush implementation, so apply it there too.

Original-by: David Matlack 
Signed-off-by: Jing Zhang 
Message-Id: <20210817002639.3856694-1-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini

KVM: stats: Add halt polling related histogram stats

2021-08-20T20:06:33+00:00

Add three log histogram stats to record the distribution of time spent
on successful polling, failed polling and VCPU wait.
halt_poll_success_hist: Distribution of spent time for a successful poll.
halt_poll_fail_hist: Distribution of spent time for a failed poll.
halt_wait_hist: Distribution of time a VCPU has spent on waiting.

Signed-off-by: Jing Zhang 
Message-Id: <20210802165633.1866976-6-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini

KVM: stats: Add halt_wait_ns stats for all architectures

2021-08-20T20:06:33+00:00

Add simple stats halt_wait_ns to record the time a VCPU has spent on
waiting for all architectures (not just powerpc).

Signed-off-by: Jing Zhang 
Message-Id: <20210802165633.1866976-5-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini

KVM: stats: Support linear and logarithmic histogram statistics

2021-08-20T20:06:32+00:00

Add new types of KVM stats, linear and logarithmic histogram.
Histogram are very useful for observing the value distribution
of time or size related stats.

Signed-off-by: Jing Zhang 
Message-Id: <20210802165633.1866976-2-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini

KVM: x86/mmu: bump mmu notifier count in kvm_zap_gfn_range

2021-08-20T20:06:19+00:00

This together with previous patch, ensures that
kvm_zap_gfn_range doesn't race with page fault
running on another vcpu, and will make this page fault code
retry instead.

This is based on a patch suggested by Sean Christopherson:
https://lkml.org/lkml/2021/7/22/1025

Suggested-by: Sean Christopherson 
Signed-off-by: Maxim Levitsky 
Message-Id: <20210810205251.424103-5-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini

KVM: Allow to have arch-specific per-vm debugfs files

2021-08-13T07:35:17+00:00

Allow archs to create arch-specific nodes under kvm->debugfs_dentry directory
besides the stats fields.  The new interface kvm_arch_create_vm_debugfs() is
defined but not yet used.  It's called after kvm->debugfs_dentry is created, so
it can be referenced directly in kvm_arch_create_vm_debugfs().  Arch should
define their own versions when they want to create extra debugfs nodes.

Signed-off-by: Peter Xu 
Message-Id: <20210730220455.26054-2-peterx@redhat.com>
Signed-off-by: Paolo Bonzini

KVM: Cache the last used slot index per vCPU

2021-08-06T11:52:29+00:00

The memslot for a given gfn is looked up multiple times during page
fault handling. Avoid binary searching for it multiple times by caching
the most recently used slot. There is an existing VM-wide last_used_slot
but that does not work well for cases where vCPUs are accessing memory
in different slots (see performance data below).

Another benefit of caching the most recently use slot (versus looking
up the slot once and passing around a pointer) is speeding up memslot
lookups *across* faults and during spte prefetching.

To measure the performance of this change I ran dirty_log_perf_test with
64 vCPUs and 64 memslots and measured "Populate memory time" and
"Iteration 2 dirty memory time".  Tests were ran with eptad=N to force
dirty logging to use fast_page_fault so its performance could be
measured.

Config     | Metric                        | Before | After
---------- | ----------------------------- | ------ | ------
tdp_mmu=Y  | Populate memory time          | 6.76s  | 5.47s
tdp_mmu=Y  | Iteration 2 dirty memory time | 2.83s  | 0.31s
tdp_mmu=N  | Populate memory time          | 20.4s  | 18.7s
tdp_mmu=N  | Iteration 2 dirty memory time | 2.65s  | 0.30s

The "Iteration 2 dirty memory time" results are especially compelling
because they are equivalent to running the same test with a single
memslot. In other words, fast_page_fault performance no longer scales
with the number of memslots.

Signed-off-by: David Matlack 
Message-Id: <20210804222844.1419481-4-dmatlack@google.com>
Signed-off-by: Paolo Bonzini

KVM: Move last_used_slot logic out of search_memslots

2021-08-06T11:52:28+00:00

Make search_memslots unconditionally search all memslots and move the
last_used_slot logic up one level to __gfn_to_memslot. This is in
preparation for introducing a per-vCPU last_used_slot.

As part of this change convert existing callers of search_memslots to
__gfn_to_memslot to avoid making any functional changes.

Signed-off-by: David Matlack 
Message-Id: <20210804222844.1419481-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini

KVM: Rename lru_slot to last_used_slot

2021-08-06T11:52:28+00:00

lru_slot is used to keep track of the index of the most-recently used
memslot. The correct acronym would be "mru" but that is not a common
acronym. So call it last_used_slot which is a bit more obvious.

Suggested-by: Paolo Bonzini 
Signed-off-by: David Matlack 
Message-Id: <20210804222844.1419481-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini