Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
To:     Sami Tolvanen <samitolvanen@google.com>
Subject: Re: [PATCH v4 03/17] arm64: kvm: stop treating register x18 as  caller save
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8;
 format=flowed
Content-Transfer-Encoding: 7bit
Date:   Mon, 04 Nov 2019 12:13:00 +0109
From:   Marc Zyngier <maz@kernel.org>
Cc:     Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Dave Martin <dave.martin@arm.com>,
        Kees Cook <keescook@chromium.org>,
        Laura Abbott <labbott@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Jann Horn <jannh@google.com>,
        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        <clang-built-linux@googlegroups.com>,
        <kernel-hardening@lists.openwall.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
In-Reply-To: <20191101221150.116536-4-samitolvanen@google.com>
References: <20191018161033.261971-1-samitolvanen@google.com>
 <20191101221150.116536-1-samitolvanen@google.com>
 <20191101221150.116536-4-samitolvanen@google.com>
Message-ID: <79e8f958cbde52a3d90aec24dd4638d9@www.loen.fr>
User-Agent: Roundcube Webmail/0.7.2
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Sami,

On 2019-11-01 23:20, Sami Tolvanen wrote:
> From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>
> In preparation of reserving x18, stop treating it as caller save in
> the KVM guest entry/exit code. Currently, the code assumes there is
> no need to preserve it for the host, given that it would have been
> assumed clobbered anyway by the function call to __guest_enter().
> Instead, preserve its value and restore it upon return.
>
> Link: https://patchwork.kernel.org/patch/9836891/
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> [Sami: updated commit message, switched from x18 to x29 for the guest
> context]
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>

If you intend for this to be merged via the arm64 tree, please add my

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...