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([2001:8003:e5b0:9f00:dbbc:1945:6e65:ec5]) by smtp.gmail.com with ESMTPSA id q22-20020a170902bd9600b001bb9f104328sm7342815pls.146.2023.09.17.21.38.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 17 Sep 2023 21:38:17 -0700 (PDT) Message-ID: <7b5f8dda-93c9-6338-15a5-acf76910c35b@redhat.com> Date: Mon, 18 Sep 2023 14:38:09 +1000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [RFC PATCH v2 14/35] ACPI: Only enumerate enabled (or functional) devices Content-Language: en-US To: Jonathan Cameron , James Morse Cc: linux-pm@vger.kernel.org, loongarch@lists.linux.dev, linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, kvmarm@lists.linux.dev, x86@kernel.org, Salil Mehta , Russell King , Jean-Philippe Brucker , jianyong.wu@arm.com, justin.he@arm.com References: <20230913163823.7880-1-james.morse@arm.com> <20230913163823.7880-15-james.morse@arm.com> <20230914132732.00006908@Huawei.com> From: Gavin Shan In-Reply-To: <20230914132732.00006908@Huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/14/23 22:27, Jonathan Cameron wrote: > On Wed, 13 Sep 2023 16:38:02 +0000 > James Morse wrote: > >> Today the ACPI enumeration code 'visits' all devices that are present. >> >> This is a problem for arm64, where CPUs are always present, but not >> always enabled. When a device-check occurs because the firmware-policy >> has changed and a CPU is now enabled, the following error occurs: >> | acpi ACPI0007:48: Enumeration failure >> >> This is ultimately because acpi_dev_ready_for_enumeration() returns >> true for a device that is not enabled. The ACPI Processor driver >> will not register such CPUs as they are not 'decoding their resources'. >> >> Change acpi_dev_ready_for_enumeration() to also check the enabled bit. >> ACPI allows a device to be functional instead of maintaining the >> present and enabled bit. Make this behaviour an explicit check with >> a reference to the spec, and then check the present and enabled bits. > > "and the" only applies if the functional route hasn't been followed > "if not this case check the present and enabled bits." > >> This is needed to avoid enumerating present && functional devices that >> are not enabled. >> >> Signed-off-by: James Morse >> --- >> If this change causes problems on deployed hardware, I suggest an >> arch opt-in: ACPI_IGNORE_STA_ENABLED, that causes >> acpi_dev_ready_for_enumeration() to only check the present bit. >> --- >> drivers/acpi/device_pm.c | 2 +- >> drivers/acpi/device_sysfs.c | 2 +- >> drivers/acpi/internal.h | 1 - >> drivers/acpi/property.c | 2 +- >> drivers/acpi/scan.c | 23 +++++++++++++---------- >> 5 files changed, 16 insertions(+), 14 deletions(-) >> >> diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c >> index f007116a8427..76c38478a502 100644 >> --- a/drivers/acpi/device_pm.c >> +++ b/drivers/acpi/device_pm.c >> @@ -313,7 +313,7 @@ int acpi_bus_init_power(struct acpi_device *device) >> return -EINVAL; >> >> device->power.state = ACPI_STATE_UNKNOWN; >> - if (!acpi_device_is_present(device)) { >> + if (!acpi_dev_ready_for_enumeration(device)) { >> device->flags.initialized = false; >> return -ENXIO; >> } >> diff --git a/drivers/acpi/device_sysfs.c b/drivers/acpi/device_sysfs.c >> index b9bbf0746199..16e586d74aa2 100644 >> --- a/drivers/acpi/device_sysfs.c >> +++ b/drivers/acpi/device_sysfs.c >> @@ -141,7 +141,7 @@ static int create_pnp_modalias(const struct acpi_device *acpi_dev, char *modalia >> struct acpi_hardware_id *id; >> >> /* Avoid unnecessarily loading modules for non present devices. */ >> - if (!acpi_device_is_present(acpi_dev)) >> + if (!acpi_dev_ready_for_enumeration(acpi_dev)) >> return 0; >> >> /* >> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h >> index 866c7c4ed233..a1b45e345bcc 100644 >> --- a/drivers/acpi/internal.h >> +++ b/drivers/acpi/internal.h >> @@ -107,7 +107,6 @@ int acpi_device_setup_files(struct acpi_device *dev); >> void acpi_device_remove_files(struct acpi_device *dev); >> void acpi_device_add_finalize(struct acpi_device *device); >> void acpi_free_pnp_ids(struct acpi_device_pnp *pnp); >> -bool acpi_device_is_present(const struct acpi_device *adev); >> bool acpi_device_is_battery(struct acpi_device *adev); >> bool acpi_device_is_first_physical_node(struct acpi_device *adev, >> const struct device *dev); >> diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c >> index 413e4fcadcaf..e03f00b98701 100644 >> --- a/drivers/acpi/property.c >> +++ b/drivers/acpi/property.c >> @@ -1418,7 +1418,7 @@ static bool acpi_fwnode_device_is_available(const struct fwnode_handle *fwnode) >> if (!is_acpi_device_node(fwnode)) >> return false; >> >> - return acpi_device_is_present(to_acpi_device_node(fwnode)); >> + return acpi_dev_ready_for_enumeration(to_acpi_device_node(fwnode)); >> } >> >> static const void * >> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c >> index 17ab875a7d4e..f898591ce05f 100644 >> --- a/drivers/acpi/scan.c >> +++ b/drivers/acpi/scan.c >> @@ -304,7 +304,7 @@ static int acpi_scan_device_check(struct acpi_device *adev) >> int error; >> >> acpi_bus_get_status(adev); >> - if (acpi_device_is_present(adev)) { >> + if (acpi_dev_ready_for_enumeration(adev)) { >> /* >> * This function is only called for device objects for which >> * matching scan handlers exist. The only situation in which >> @@ -338,7 +338,7 @@ static int acpi_scan_bus_check(struct acpi_device *adev, void *not_used) >> int error; >> >> acpi_bus_get_status(adev); >> - if (!acpi_device_is_present(adev)) { >> + if (!acpi_dev_ready_for_enumeration(adev)) { >> acpi_scan_device_not_enumerated(adev); >> return 0; >> } >> @@ -1908,11 +1908,6 @@ static bool acpi_device_should_be_hidden(acpi_handle handle) >> return true; >> } >> >> -bool acpi_device_is_present(const struct acpi_device *adev) >> -{ >> - return adev->status.present || adev->status.functional; >> -} >> - >> static bool acpi_scan_handler_matching(struct acpi_scan_handler *handler, >> const char *idstr, >> const struct acpi_device_id **matchid) >> @@ -2375,16 +2370,24 @@ EXPORT_SYMBOL_GPL(acpi_dev_clear_dependencies); >> * acpi_dev_ready_for_enumeration - Check if the ACPI device is ready for enumeration >> * @device: Pointer to the &struct acpi_device to check >> * >> - * Check if the device is present and has no unmet dependencies. >> + * Check if the device is functional or enabled and has no unmet dependencies. >> * >> - * Return true if the device is ready for enumeratino. Otherwise, return false. >> + * Return true if the device is ready for enumeration. Otherwise, return false. >> */ >> bool acpi_dev_ready_for_enumeration(const struct acpi_device *device) >> { >> if (device->flags.honor_deps && device->dep_unmet) >> return false; >> >> - return acpi_device_is_present(device); >> + /* >> + * ACPI 6.5's 6.3.7 "_STA (Device Status)" allows firmware to return >> + * (!present && functional) for certain types of devices that should be >> + * enumerated. > > I'd call out the fact that enumeration isn't same as "device driver should be loaded" > which is the thing that functional is supposed to indicate should not happen. > >> + */ >> + if (!device->status.present && !device->status.enabled) > > In theory no need to check !enabled if !present > "If bit [0] is cleared, then bit 1 must also be cleared (in other words, a device that is not present cannot be enabled)." > We could report an ACPI bug if that's seen. If that bug case is ignored this code can > become the simpler. > > if (device->status.present) > return device->status_enabled; > else > return device->status.functional; > > Or the following also valid here (as functional should be set for enabled present devices > unless they failed diagnostics). > > if (dev->status.functional) > return true; > return device->status.present && device->status.enabled; > > On assumption we want to enumerate dead devices for debug purposes... > I think it's worthy to include the words about the synchronization between present/enabled bits into comments, outlined by Jonathan, to help readers to understand the code. Something like below for the comments: /* * ACPI 6.5's 6.3.7 "_STA (Device Status)" allows firmware to return * (!present && functional) for certain types of devices that should be * enumerated. Note that the enabled bit can't be set until the present * bit is set. */ > >> + return device->status.functional; >> + >> + return device->status.present && device->status.enabled; > > >> } >> EXPORT_SYMBOL_GPL(acpi_dev_ready_for_enumeration); >> Thanks, Gavin