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Sat, 10 Sep 2022 15:20:35 +0100 Date: Sat, 10 Sep 2022 15:20:35 +0100 Message-ID: <871qsjqpjg.wl-maz@kernel.org> From: Marc Zyngier To: Will Deacon Cc: Elliot Berman , Catalin Marinas , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu Subject: Re: [PATCH v2] KVM: arm64: Only set KVM_MODE_PROTECTED if is_hyp_mode_available() In-Reply-To: <20220910134342.GA959@willie-the-truck> References: <20220909144552.3000716-1-quic_eberman@quicinc.com> <05057e2a-1a85-69ba-ffcd-584d4090467a@quicinc.com> <878rmrr3xw.wl-maz@kernel.org> <20220910134342.GA959@willie-the-truck> 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/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: will@kernel.org, quic_eberman@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu 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-20220910_072042_405386_9E880669 X-CRM114-Status: GOOD ( 32.53 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sat, 10 Sep 2022 14:43:44 +0100, Will Deacon wrote: > > On Sat, Sep 10, 2022 at 10:09:31AM +0100, Marc Zyngier wrote: > > On Fri, 09 Sep 2022 18:55:18 +0100, > > Elliot Berman wrote: > > > > > > > > > > > > On 9/9/2022 10:28 AM, Catalin Marinas wrote: > > > > On Fri, Sep 09, 2022 at 07:45:52AM -0700, Elliot Berman wrote: > > > >> Do not switch kvm_mode to KVM_MODE_PROTECTED if hypervisor mode is not > > > >> available. This prevents "Protected KVM" cpu capability being reported > > > >> when Linux is booting in EL1 and would not have KVM enabled. > > > >> > > > >> Signed-off-by: Elliot Berman > > > >> --- > > > >> arch/arm64/kvm/arm.c | 4 +++- > > > >> 1 file changed, 3 insertions(+), 1 deletion(-) > > > >> > > > >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > > > >> index 8fe73ee5fa84..861f4b388879 100644 > > > >> --- a/arch/arm64/kvm/arm.c > > > >> +++ b/arch/arm64/kvm/arm.c > > > >> @@ -2272,7 +2272,9 @@ static int __init early_kvm_mode_cfg(char *arg) > > > >> return -EINVAL; > > > >> if (strcmp(arg, "protected") == 0) { > > > >> - if (!is_kernel_in_hyp_mode()) > > > >> + if (!is_hyp_mode_available()) > > > >> + kvm_mode = KVM_MODE_DEFAULT; > > > > > > > > I think kvm_mode is already KVM_MODE_DEFAULT at this point. You may want > > > > to print a warning instead. > > > > > > > > > > Does it make sense to print warning for kvm-arm.mode=nvhe as well? > > > > In general, specifying a kvm-arm.mode when no hypervisor mode is > > available should be reported as a warning. > > As long as this is pr_warn() rather than WARN() then I agree. Otherwise, > kernels with a kvm-arm.mode hardcoded in CONFIG_CMDLINE (e.g. Android's > GKI) will make for noisy guests. Indeed, pr_warn() is what I had in mind. A WARN() would be pretty overkill, as there is nothing majorly wrong with booting at EL1, just an impossibility to honour the request from the command line. M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel