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Re: [PATCH v4 2/2] drivers/char: Use sub-page ro API to make just xhci dbc cap RO
- To: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 23 May 2024 10:22:42 +0200
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Thu, 23 May 2024 08:22:47 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 22.05.2024 17:39, Marek Marczykowski-Górecki wrote:
> Not the whole page, which may contain other registers too. The XHCI
> specification describes DbC as designed to be controlled by a different
> driver, but does not mandate placing registers on a separate page. In fact
> on Tiger Lake and newer (at least), this page do contain other registers
> that Linux tries to use. And with share=yes, a domU would use them too.
> Without this patch, PV dom0 would fail to initialize the controller,
> while HVM would be killed on EPT violation.
>
> With `share=yes`, this patch gives domU more access to the emulator
> (although a HVM with any emulated device already has plenty of it). This
> configuration is already documented as unsafe with untrusted guests and
> not security supported.
>
> Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
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