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Thu, 24 Oct 2024 10:39:45 +0100 Date: Thu, 24 Oct 2024 10:39:45 +0100 Message-ID: <86v7xh3km6.wl-maz@kernel.org> From: Marc Zyngier To: Mostafa Saleh Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, corbet@lwn.net, Will Deacon Subject: Re: [PATCH] Documentation: Update the behaviour of "kvm-arm.mode" In-Reply-To: <20241023171244.4031151-1-smostafa@google.com> References: <20241023171244.4031151-1-smostafa@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.4 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: smostafa@google.com, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, corbet@lwn.net, will@kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241024_023950_287165_9C4253CD X-CRM114-Status: GOOD ( 23.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Mostafa, On Wed, 23 Oct 2024 18:12:43 +0100, Mostafa Saleh wrote: > > Commit 5053c3f0519c ("KVM: arm64: Use hVHE in pKVM by default on CPUs with > VHE support") modified the behaviour of "kvm-arm.mode=protected" without > the updating the kernel parameters doc. > > Update it to match the current implementation. > > Cc: Will Deacon > Cc: Marc Zyngier > > Signed-off-by: Mostafa Saleh > --- > Documentation/admin-guide/kernel-parameters.txt | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index bb48ae24ae69..59a0dd7e2de6 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2723,8 +2723,12 @@ > nvhe: Standard nVHE-based mode, without support for > protected guests. > > - protected: nVHE-based mode with support for guests whose > + protected: hVHE-based mode with support for guests whose > state is kept private from the host. > + In case hVHE is not supported in hardware, it will nit: it is VHE that is supported or not, hVHE is only a SW concept. > + boot with protected nVHE. > + nVHE protected mode can still be forced on VHE systems > + using "kvm_arm.mode=protected arm64_sw.hvhe=0 id_aa64mmfr1.vh=0" This opens another question: none of the arm_sw.*, nor any of the id_aa64* parameters are described (basically, anything that's in arch/arm64/kernel/pi/id_override.c). What should we do about these? > > nested: VHE-based mode with support for nested > virtualization. Requires at least ARMv8.3 Huh, another nit to fix. We only support nested with ARMv8.4 (with FEAT_NV2), as the ARMv8.3 version (the original FEAT_NV) is too ugly for words. Mind addressing this? Thanks! M. -- Without deviation from the norm, progress is not possible.