On Fri, Sep 02, 2022 at 04:26:57PM +0200, Ben Hutchings wrote:
On Thu, 2022-09-01 at 11:43 +0200, Greg KH wrote:
On Mon, Aug 29, 2022 at 04:04:58PM +0200, Ben Hutchings wrote:
On Mon, 2022-08-29 at 10:30 +0200, gregkh@linuxfoundation.org wrote:
The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
You need commit 4e3aa9238277 "x86/nospec: Unwreck the RSB stuffing" before this one. I've attached the backport of that for 5.10. I haven't checked the older branches.
Great, thanks, this worked. But the backport did not apply to 4.19, so I will need that in order to take this one as well.
I've had a look at 5.4, and it's sufficiently different from upstream that I don't see how to move forward.
However, I also found that the PBRSB mitigation seems broken, as commit fc02735b14ff "KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS" was not backported (and would be hard to add).
So, perhaps it would be best to revert the backports of:
2b1299322016 x86/speculation: Add RSB VM Exit protections ba6e31af2be9 x86/speculation: Add LFENCE to RSB fill sequence
in stable branches older than 5.10.
Why? Is it because they do not work at all there, or are they causing problems?
thanks,
greg k-h