Anthony Liguori wrote:
> Howdy,
>
> Attached patch implements lazy-fpu save/restore for VT. VMEXIT time
> improves by about 10% (~550 cycles). I had to do a couple more things
> to get it working than I had to do with SVM. I changed the CR0 host
> mask to be all 1's so that any attempt to write to CR0 causes a
> VMEXIT. I don't think there are any remaining bits now that we want
> to trap TS that are safe for the guest to access and are in the
> fast-paths.
Great! With a couple more msrs we'll get to 50% off what we had two
weeks ago.
>
> Since we're trapping TS, I had to implement CLTS exit handling.
> vcpu->cr0 also had a rather bizarre life cycle. After a set_cr0, it
> was a proper shadow of the guest's CR0. However, after a decache_cr0,
> it would contain the host's version of the bits covered by the CR0
> host mask so it was no longer a proper shadow.
>
> I got rid of the CR0 caching and made vcpu->cr0 always be equivalent
> to CR0_READ_SHADOW. Once these changes were made, the rest of the
> patch was much like the SVM one.
>
>
> - if ((intr_info & INTR_INFO_INTR_TYPE_MASK) == 0x200) { /* nmi */
> + switch (intr_info & INTR_INFO_VECTOR_MASK) {
> + case NMI_VECTOR:
> asm ("int $2");
> return 1;
> + case NM_VECTOR:
> + vcpu->fpu_active = 1;
> + vmcs_clear_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR);
> + if (!(vcpu->cr0 & CR0_TS_MASK))
> + vmcs_clear_bits(GUEST_CR0, CR0_TS_MASK);
> + return 1;
> }
>
I'd like to be conservative here and not depend just on the vector:
check type == 2 for nmi, and type == 6, vector == NM for #NM. In fact,
I see that is_page_fault() and is_external_interrupt() implement
something like that already.
Also, can you split the patch into the cr0 cache fix and the lazy fpu?
--
error compiling committee.c: too many arguments to function
-------------------------------------------------------------------------
This SF.net email is sponsored by DB2 Express
Download DB2 Express C - the FREE version of DB2 express and take
control of your XML. No limits. Just data. Click to get it now.
http://sourceforge.net/powerbar/db2/
_______________________________________________
kvm-devel mailing list
kvm-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/kvm-devel
