From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
Xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH for-4.16] x86/shstk: Fix use of shadow stacks with XPTI active
Date: Tue, 2 Nov 2021 16:14:19 +0100 [thread overview]
Message-ID: <29c59040-a2bc-69d3-db02-1345b5aa2b8b@suse.com> (raw)
In-Reply-To: <20211102143935.17473-1-andrew.cooper3@citrix.com>
On 02.11.2021 15:39, Andrew Cooper wrote:
> The call to setup_cpu_root_pgt(0) in smp_prepare_cpus() is too early. It
> clones the BSP's stack while the .data mapping is still in use, causing all
> mappings to be fully read read/write (and with no guard pages either). This
> ultimately causes #DF when trying to enter the dom0 kernel for the first time.
>
> Defer setting up BSPs XPTI pagetable until reinit_bsp_stack() after we've set
> up proper shadow stack permissions.
>
> Fixes: 60016604739b ("x86/shstk: Rework the stack layout to support shadow stacks")
> Fixes: b60ab42db2f0 ("x86/shstk: Activate Supervisor Shadow Stacks")
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
next prev parent reply other threads:[~2021-11-02 15:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-02 14:39 [PATCH for-4.16] x86/shstk: Fix use of shadow stacks with XPTI active Andrew Cooper
2021-11-02 15:14 ` Jan Beulich [this message]
2021-11-02 15:53 ` Ian Jackson
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