On Wed, Jun 24, 2020 at 12:00:59PM +0000, Rantala, Tommi T. (Nokia - FI/Espoo) wrote:
On Fri, 2020-06-19 at 16:31 +0200, Greg Kroah-Hartman wrote:
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
[ Upstream commit d43e2675e96fc6ae1a633b6a69d296394448cc32 ]
KVM stores the gfn in MMIO SPTEs as a caching optimization. These are
split
in two parts, as in "[high 11111 low]", to thwart any attempt to use these
bits
in an L1TF attack. This works as long as there are 5 free bits between
MAXPHYADDR and bit 50 (inclusive), leaving bit 51 free so that the MMIO
access triggers a reserved-bit-set page fault.
Hi, I'm now seeing this warning in VM bootup with 4.14.y
Thanks for the report!
Not seen with 4.19.129 and 5.4.47 that also included this commit.
Any ideas what's missing in 4.14 ?
I think that this was because we're missing 6129ed877d40 ("KVM: x86/mmu:
Set mmio_value to '0' if reserved #PF can't be generated"). I've queued
it up (along with a few other related commits) and a new -rc cycle
should be underway for those.
--
Thanks,
Sasha
