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Re: [PATCH][4.15] x86: mirror compat argument translation area for 32-bit PV
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Roger Pau Monné <roger.pau@xxxxxxxxxx>
- Date: Mon, 22 Feb 2021 12:35:21 +0100
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- Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "Andrew Cooper" <andrew.cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Ian Jackson <iwj@xxxxxxxxxxxxxx>
- Delivery-date: Mon, 22 Feb 2021 11:35:39 +0000
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On Mon, Feb 22, 2021 at 11:27:07AM +0100, Jan Beulich wrote:
> Now that we guard the entire Xen VA space against speculative abuse
> through hypervisor accesses to guest memory, the argument translation
> area's VA also needs to live outside this range, at least for 32-bit PV
> guests. To avoid extra is_hvm_*() conditionals, use the alternative VA
> uniformly.
Since you are double mapping the per-domain virtual area, won't it
make more sense to map it just once outside of the Xen virtual space
area? (so it's always using PML4_ADDR(511))
Is there anything concerning in the per-domain area that should be
protected against speculative accesses?
Thanks, Roger.
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