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authorDavid Woodhouse <dwmw@amazon.co.uk>2021-12-10 16:36:21 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2022-01-07 10:44:44 -0500
commit982ed0de4753ed6e71dbd40f82a5a066baf133ed (patch)
tree7e74f3f9c27defff3329325ffeada66f2b84e513 /virt/kvm/Kconfig
parent2efd61a608b0039911924d2e5d7028eb37496e85 (diff)
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>
Diffstat (limited to 'virt/kvm/Kconfig')
-rw-r--r--virt/kvm/Kconfig3
1 files changed, 3 insertions, 0 deletions
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 97cf5413ac25..f4834c20e4a6 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -4,6 +4,9 @@
config HAVE_KVM
bool
+config HAVE_KVM_PFNCACHE
+ bool
+
config HAVE_KVM_IRQCHIP
bool