linux.git/include/linux/kvm_host.h, branch v5.7-rc2

KVM: Pass kvm_init()'s opaque param to additional arch funcs

2020-03-31T14:48:03+00:00

Pass @opaque to kvm_arch_hardware_setup() and
kvm_arch_check_processor_compat() to allow architecture specific code to
reference @opaque without having to stash it away in a temporary global
variable.  This will enable x86 to separate its vendor specific callback
ops, which are passed via @opaque, into "init" and "runtime" ops without
having to stash away the "init" ops.

No functional change intended.

Reviewed-by: Cornelia Huck 
Tested-by: Cornelia Huck  #s390
Acked-by: Marc Zyngier 
Signed-off-by: Sean Christopherson 
Message-Id: <20200321202603.19355-2-sean.j.christopherson@intel.com>
Reviewed-by: Vitaly Kuznetsov 
Signed-off-by: Paolo Bonzini

Merge tag 'kvmarm-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

2020-03-31T14:44:53+00:00

KVM/arm updates for Linux 5.7

- GICv4.1 support
- 32bit host removal

KVM: Fix out of range accesses to memslots

2020-03-26T09:58:27+00:00

Reset the LRU slot if it becomes invalid when deleting a memslot to fix
an out-of-bounds/use-after-free access when searching through memslots.

Explicitly check for there being no used slots in search_memslots(), and
in the caller of s390's approximation variant.

Fixes: 36947254e5f9 ("KVM: Dynamically size memslot array based on number of used slots")
Reported-by: Qian Cai 
Cc: Peter Xu 
Signed-off-by: Sean Christopherson 
Message-Id: <20200320205546.2396-2-sean.j.christopherson@intel.com>
Acked-by: Christian Borntraeger 
Signed-off-by: Paolo Bonzini

KVM: Drop largepages_enabled and its accessor/mutator

2020-03-16T16:58:42+00:00

Drop largepages_enabled, kvm_largepages_enabled() and
kvm_disable_largepages() now that all users are gone.

Note, largepages_enabled was an x86-only flag that got left in common
KVM code when KVM gained support for multiple architectures.

No functional change intended.

Reviewed-by: Vitaly Kuznetsov 
Signed-off-by: Sean Christopherson 
Signed-off-by: Paolo Bonzini

KVM: Drop gfn_to_pfn_atomic()

2020-03-16T16:57:48+00:00

It's never used anywhere now.

Signed-off-by: Peter Xu 
Signed-off-by: Paolo Bonzini

KVM: x86: enable dirty log gradually in small chunks

2020-03-16T16:57:37+00:00

It could take kvm->mmu_lock for an extended period of time when
enabling dirty log for the first time. The main cost is to clear
all the D-bits of last level SPTEs. This situation can benefit from
manual dirty log protect as well, which can reduce the mmu_lock
time taken. The sequence is like this:

1. Initialize all the bits of the dirty bitmap to 1 when enabling
   dirty log for the first time
2. Only write protect the huge pages
3. KVM_GET_DIRTY_LOG returns the dirty bitmap info
4. KVM_CLEAR_DIRTY_LOG will clear D-bit for each of the leaf level
   SPTEs gradually in small chunks

Under the Intel(R) Xeon(R) Gold 6152 CPU @ 2.10GHz environment,
I did some tests with a 128G windows VM and counted the time taken
of memory_global_dirty_log_start, here is the numbers:

VM Size        Before    After optimization
128G           460ms     10ms

Signed-off-by: Jay Zhou 
Signed-off-by: Paolo Bonzini

KVM: Dynamically size memslot array based on number of used slots

2020-03-16T16:57:26+00:00

Now that the memslot logic doesn't assume memslots are always non-NULL,
dynamically size the array of memslots instead of unconditionally
allocating memory for the maximum number of memslots.

Note, because a to-be-deleted memslot must first be invalidated, the
array size cannot be immediately reduced when deleting a memslot.
However, consecutive deletions will realize the memory savings, i.e.
a second deletion will trim the entry.

Tested-by: Christoffer Dall 
Tested-by: Marc Zyngier 
Reviewed-by: Peter Xu 
Signed-off-by: Sean Christopherson 
Signed-off-by: Paolo Bonzini

KVM: Terminate memslot walks via used_slots

2020-03-16T16:57:26+00:00

Refactor memslot handling to treat the number of used slots as the de
facto size of the memslot array, e.g. return NULL from id_to_memslot()
when an invalid index is provided instead of relying on npages==0 to
detect an invalid memslot.  Rework the sorting and walking of memslots
in advance of dynamically sizing memslots to aid bisection and debug,
e.g. with luck, a bug in the refactoring will bisect here and/or hit a
WARN instead of randomly corrupting memory.

Alternatively, a global null/invalid memslot could be returned, i.e. so
callers of id_to_memslot() don't have to explicitly check for a NULL
memslot, but that approach runs the risk of introducing difficult-to-
debug issues, e.g. if the global null slot is modified.  Constifying
the return from id_to_memslot() to combat such issues is possible, but
would require a massive refactoring of arch specific code and would
still be susceptible to casting shenanigans.

Add function comments to update_memslots() and search_memslots() to
explicitly (and loudly) state how memslots are sorted.

Opportunistically stuff @hva with a non-canonical value when deleting a
private memslot on x86 to detect bogus usage of the freed slot.

No functional change intended.

Tested-by: Christoffer Dall 
Tested-by: Marc Zyngier 
Signed-off-by: Sean Christopherson 
Signed-off-by: Paolo Bonzini

KVM: Ensure validity of memslot with respect to kvm_get_dirty_log()

2020-03-16T16:57:25+00:00

Rework kvm_get_dirty_log() so that it "returns" the associated memslot
on success.  A future patch will rework memslot handling such that
id_to_memslot() can return NULL, returning the memslot makes it more
obvious that the validity of the memslot has been verified, i.e.
precludes the need to add validity checks in the arch code that are
technically unnecessary.

To maintain ordering in s390, move the call to kvm_arch_sync_dirty_log()
from s390's kvm_vm_ioctl_get_dirty_log() to the new kvm_get_dirty_log().
This is a nop for PPC, the only other arch that doesn't select
KVM_GENERIC_DIRTYLOG_READ_PROTECT, as its sync_dirty_log() is empty.

Ideally, moving the sync_dirty_log() call would be done in a separate
patch, but it can't be done in a follow-on patch because that would
temporarily break s390's ordering.  Making the move in a preparatory
patch would be functionally correct, but would create an odd scenario
where the moved sync_dirty_log() would operate on a "different" memslot
due to consuming the result of a different id_to_memslot().  The
memslot couldn't actually be different as slots_lock is held, but the
code is confusing enough as it is, i.e. moving sync_dirty_log() in this
patch is the lesser of all evils.

Signed-off-by: Sean Christopherson 
Signed-off-by: Paolo Bonzini

KVM: Provide common implementation for generic dirty log functions

2020-03-16T16:57:24+00:00

Move the implementations of KVM_GET_DIRTY_LOG and KVM_CLEAR_DIRTY_LOG
for CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT into common KVM code.
The arch specific implemenations are extremely similar, differing
only in whether the dirty log needs to be sync'd from hardware (x86)
and how the TLBs are flushed.  Add new arch hooks to handle sync
and TLB flush; the sync will also be used for non-generic dirty log
support in a future patch (s390).

The ulterior motive for providing a common implementation is to
eliminate the dependency between arch and common code with respect to
the memslot referenced by the dirty log, i.e. to make it obvious in the
code that the validity of the memslot is guaranteed, as a future patch
will rework memslot handling such that id_to_memslot() can return NULL.

Signed-off-by: Sean Christopherson 
Signed-off-by: Paolo Bonzini