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Tue, 10 Nov 2020 14:43:02 +0000 MIME-Version: 1.0 Date: Tue, 10 Nov 2020 14:43:01 +0000 From: Marc Zyngier To: David Brazdil Subject: Re: [PATCH v1 01/24] psci: Accessor for configured PSCI version In-Reply-To: <20201109113233.9012-2-dbrazdil@google.com> References: <20201109113233.9012-1-dbrazdil@google.com> <20201109113233.9012-2-dbrazdil@google.com> User-Agent: Roundcube Webmail/1.4.9 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: dbrazdil@google.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, catalin.marinas@arm.com, will@kernel.org, dennis@kernel.org, tj@kernel.org, cl@linux.com, mark.rutland@arm.com, lorenzo.pieralisi@arm.com, qperret@google.com, ascull@google.com, qwandor@google.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: kernel-team@android.com, Lorenzo Pieralisi , Andrew Walbran , Catalin Marinas , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Tejun Heo , Dennis Zhou , Christoph Lameter , Will Deacon , kvmarm@lists.cs.columbia.edu X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 2020-11-09 11:32, David Brazdil wrote: > The version of PSCI that the kernel should use to communicate with > firmware is typically obtained from probing PSCI_VERSION. However, that > doesn't work for PSCI v0.1 where the host gets the information from > DT/ACPI, or if PSCI is not supported / was disabled. > > KVM's host PSCI proxy needs to be configured with the same version > used by the host driver. Expose the PSCI version used by the host > with a read-only accessor. > > Signed-off-by: David Brazdil > --- > drivers/firmware/psci/psci.c | 11 +++++++++++ > include/linux/psci.h | 8 ++++++++ > 2 files changed, 19 insertions(+) > > diff --git a/drivers/firmware/psci/psci.c > b/drivers/firmware/psci/psci.c > index 00af99b6f97c..bc1b2d60fdbf 100644 > --- a/drivers/firmware/psci/psci.c > +++ b/drivers/firmware/psci/psci.c > @@ -49,6 +49,13 @@ static int resident_cpu = -1; > struct psci_operations psci_ops; > static enum arm_smccc_conduit psci_conduit = SMCCC_CONDUIT_NONE; > > +static int driver_version = PSCI_VERSION(0, 0); > + > +int psci_driver_version(void) > +{ > + return driver_version; > +} > + > bool psci_tos_resident_on(int cpu) > { > return cpu == resident_cpu; > @@ -461,6 +468,8 @@ static int __init psci_probe(void) > return -EINVAL; > } > > + driver_version = ver; > + > psci_0_2_set_functions(); > > psci_init_migrate(); > @@ -514,6 +523,8 @@ static int __init psci_0_1_init(struct device_node > *np) > > pr_info("Using PSCI v0.1 Function IDs from DT\n"); > > + driver_version = PSCI_VERSION(0, 1); > + > if (!of_property_read_u32(np, "cpu_suspend", &id)) { > psci_function_id[PSCI_FN_CPU_SUSPEND] = id; > psci_ops.cpu_suspend = psci_cpu_suspend; > diff --git a/include/linux/psci.h b/include/linux/psci.h > index 2a1bfb890e58..5b5dcf176aa6 100644 > --- a/include/linux/psci.h > +++ b/include/linux/psci.h > @@ -21,6 +21,14 @@ bool psci_power_state_is_valid(u32 state); > int psci_set_osi_mode(bool enable); > bool psci_has_osi_support(void); > > +/** > + * The version of the PSCI specification followed by the driver. > + * This is equivalent to calling PSCI_VERSION except: > + * (a) it also works for PSCI v0.1, which does not support > PSCI_VERSION, and > + * (b) it is set to v0.0 if the PSCI driver was not initialized. > + */ > +int psci_driver_version(void); > + > struct psci_operations { > u32 (*get_version)(void); > int (*cpu_suspend)(u32 state, unsigned long entry_point); I still maintain that populating .get_version in all cases instead of duplicating an existing functionality is a better outcome. PSCI not supported would be implied by .get_version being NULL. What breaks? M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm