Re: [Qemu-discuss] Does kvm/qemu maintain tlb caches?

[Peter Maydell]

On 14 January 2015 at 07:28, ravali pullela <address@hidden> wrote:
> I would like to know if kvm maintains a cache of the mappings from guest
> virtual address to host physical address or any related mappings? Does
> flushing the host tlb entries do a flush of these mappings as well. Please
> kindly let me know on this.

KVM (ie the kernel using the hardware facilities for virtualization
support) will use whatever the hardware provides. That's quite likely
to include support in the TLB for caching guest virt to host physical
mappings. You'll need to check the CPU reference manual for the
relevant CPU architecture to see what exactly it does and what
TLB flushing operations are provided.

For QEMU we also have some caching data structures which we call a
TLB; these are used when doing pure CPU emulation and generally
map guest virtual address to host virtual address, or guest virtual
address to function pointers used for emulated device read/write.

-- PMM