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SubjectRe: [PATCH] x86/retpoline: Fill return stack buffer on vmexit
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On Wed, 2018-01-10 at 22:51 +0000, David Woodhouse wrote:
> In accordance with the Intel and AMD documentation, we need to overwrite
> all entries in the RSB on exiting a guest, to prevent malicious branch
> target predictions from affecting the host kernel. This is needed both
> for retpoline and for IBRS.
>
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
> Untested in this form although it's a variant on what we've had already.
> I have an army of machines willing to do my bidding but nested virt
> is non-trivial and I figure I might as well post it as someone else
> can probably test it in less than the time it takes me to work out how.

Now smoke tested with Intel VT-x, but not yet on AMD. Tom, would you be
able to do that?


> This implements the most pressing of the RSB stuffing documented
> by dhansen (based our discussions) in https://goo.gl/pXbvBE[unhandled content-type:application/x-pkcs7-signature]
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