linux/virt/kvm/Kconfig
David Woodhouse 982ed0de47 KVM: Reinstate gfn_to_pfn_cache with invalidation support
This can be used in two modes. There is an atomic mode where the cached
mapping is accessed while holding the rwlock, and a mode where the
physical address is used by a vCPU in guest mode.

For the latter case, an invalidation will wake the vCPU with the new
KVM_REQ_GPC_INVALIDATE, and the architecture will need to refresh any
caches it still needs to access before entering guest mode again.

Only one vCPU can be targeted by the wake requests; it's simple enough
to make it wake all vCPUs or even a mask but I don't see a use case for
that additional complexity right now.

Invalidation happens from the invalidate_range_start MMU notifier, which
needs to be able to sleep in order to wake the vCPU and wait for it.

This means that revalidation potentially needs to "wait" for the MMU
operation to complete and the invalidate_range_end notifier to be
invoked. Like the vCPU when it takes a page fault in that period, we
just spin — fixing that in a future patch by implementing an actual
*wait* may be another part of shaving this particularly hirsute yak.

As noted in the comments in the function itself, the only case where
the invalidate_range_start notifier is expected to be called *without*
being able to sleep is when the OOM reaper is killing the process. In
that case, we expect the vCPU threads already to have exited, and thus
there will be nothing to wake, and no reason to wait. So we clear the
KVM_REQUEST_WAIT bit and send the request anyway, then complain loudly
if there actually *was* anything to wake up.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20211210163625.2886-3-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-07 10:44:44 -05:00

75 lines
1.1 KiB
Plaintext

# SPDX-License-Identifier: GPL-2.0
# KVM common configuration items and defaults
config HAVE_KVM
bool
config HAVE_KVM_PFNCACHE
bool
config HAVE_KVM_IRQCHIP
bool
config HAVE_KVM_IRQFD
bool
config HAVE_KVM_IRQ_ROUTING
bool
config HAVE_KVM_DIRTY_RING
bool
config HAVE_KVM_EVENTFD
bool
select EVENTFD
config KVM_MMIO
bool
config KVM_ASYNC_PF
bool
# Toggle to switch between direct notification and batch job
config KVM_ASYNC_PF_SYNC
bool
config HAVE_KVM_MSI
bool
config HAVE_KVM_CPU_RELAX_INTERCEPT
bool
config KVM_VFIO
bool
config HAVE_KVM_ARCH_TLB_FLUSH_ALL
bool
config HAVE_KVM_INVALID_WAKEUPS
bool
config KVM_GENERIC_DIRTYLOG_READ_PROTECT
bool
config KVM_COMPAT
def_bool y
depends on KVM && COMPAT && !(S390 || ARM64)
config HAVE_KVM_IRQ_BYPASS
bool
config HAVE_KVM_VCPU_ASYNC_IOCTL
bool
config HAVE_KVM_VCPU_RUN_PID_CHANGE
bool
config HAVE_KVM_NO_POLL
bool
config KVM_XFER_TO_GUEST_WORK
bool
config HAVE_KVM_PM_NOTIFIER
bool