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Mon, 18 Nov 2024 19:32:44 +0000 (GMT) Received: from nasanex01b.na.qualcomm.com (nasanex01b.na.qualcomm.com [10.46.141.250]) by NASANPPMTA02.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 4AIJWgkD018501 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 18 Nov 2024 19:32:42 GMT Received: from hu-eberman-lv.qualcomm.com (10.49.16.6) by nasanex01b.na.qualcomm.com (10.46.141.250) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Mon, 18 Nov 2024 11:30:38 -0800 Date: Mon, 18 Nov 2024 11:30:38 -0800 From: Elliot Berman To: Lorenzo Pieralisi CC: Bjorn Andersson , Sebastian Reichel , Rob Herring , Conor Dooley , Vinod Koul , Andy Yan , Mark Rutland , "Bartosz Golaszewski" , Arnd Bergmann , Olof Johansson , Catalin Marinas , Will Deacon , , Krzysztof Kozlowski , Konrad Dybcio , Satya Durga Srinivasu Prabhala , Melody Olvera , Shivendra Pratap , , , , Florian Fainelli , Stephen Boyd , , Subject: Re: [PATCH v8 3/6] firmware: psci: Read and use vendor reset types Message-ID: <20241118112859866-0800.eberman@hu-eberman-lv.qualcomm.com> References: <20241107-arm-psci-system_reset2-vendor-reboots-v8-0-e8715fa65cb5@quicinc.com> <20241107-arm-psci-system_reset2-vendor-reboots-v8-3-e8715fa65cb5@quicinc.com> <20241115103434410-0800.eberman@hu-eberman-lv.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-Originating-IP: [10.49.16.6] X-ClientProxiedBy: nalasex01b.na.qualcomm.com (10.47.209.197) To nasanex01b.na.qualcomm.com (10.46.141.250) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: 8DhnPeyG1GwH2tJoJnJsQTe0EWGLKIxH X-Proofpoint-ORIG-GUID: 8DhnPeyG1GwH2tJoJnJsQTe0EWGLKIxH X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-06_09,2024-09-06_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 suspectscore=0 malwarescore=0 mlxscore=0 adultscore=0 clxscore=1015 spamscore=0 impostorscore=0 priorityscore=1501 mlxlogscore=999 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2411180160 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241118_113255_199981_1C31D948 X-CRM114-Status: GOOD ( 65.53 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Nov 18, 2024 at 01:26:48PM +0100, Lorenzo Pieralisi wrote: > On Fri, Nov 15, 2024 at 11:08:13AM -0800, Elliot Berman wrote: > > On Fri, Nov 15, 2024 at 02:51:16PM +0100, Lorenzo Pieralisi wrote: > > > On Thu, Nov 07, 2024 at 03:38:27PM -0800, Elliot Berman wrote: > > > > SoC vendors have different types of resets and are controlled through > > > > various registers. For instance, Qualcomm chipsets can reboot to a > > > > "download mode" that allows a RAM dump to be collected. Another example > > > > is they also support writing a cookie that can be read by bootloader > > > > during next boot. PSCI offers a mechanism, SYSTEM_RESET2, for these > > > > vendor reset types to be implemented without requiring drivers for every > > > > register/cookie. > > > > > > > > Add support in PSCI to statically map reboot mode commands from > > > > userspace to a vendor reset and cookie value using the device tree. > > > > > > > > A separate initcall is needed to parse the devicetree, instead of using > > > > psci_dt_init because mm isn't sufficiently set up to allocate memory. > > > > > > Nit: information below this point is more a cover letter than for the > > > commit log. > > > > > > > Reboot mode framework is close but doesn't quite fit with the > > > > design and requirements for PSCI SYSTEM_RESET2. Some of these issues can > > > > be solved but doesn't seem reasonable in sum: > > > > 1. reboot mode registers against the reboot_notifier_list, which is too > > > > early to call SYSTEM_RESET2. PSCI would need to remember the reset > > > > type from the reboot-mode framework callback and use it > > > > psci_sys_reset. > > > > 2. reboot mode assumes only one cookie/parameter is described in the > > > > device tree. SYSTEM_RESET2 uses 2: one for the type and one for > > > > cookie. > > > > 3. psci cpuidle driver already registers a driver against the > > > > arm,psci-1.0 compatible. Refactoring would be needed to have both a > > > > cpuidle and reboot-mode driver. > > > > > > > > Tested-by: Florian Fainelli > > > > Signed-off-by: Elliot Berman > > > > --- > > > > drivers/firmware/psci/psci.c | 104 +++++++++++++++++++++++++++++++++++++++++++ > > > > 1 file changed, 104 insertions(+) > > > > > > > > diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c > > > > index 2328ca58bba61fdb677ac20a1a7447882cd0cf22..e60e3f8749c5a6732c51d23a2c1f453361132d9a 100644 > > > > --- a/drivers/firmware/psci/psci.c > > > > +++ b/drivers/firmware/psci/psci.c > > > > @@ -79,6 +79,14 @@ struct psci_0_1_function_ids get_psci_0_1_function_ids(void) > > > > static u32 psci_cpu_suspend_feature; > > > > static bool psci_system_reset2_supported; > > > > > > > > +struct psci_reset_param { > > > > + const char *mode; > > > > + u32 reset_type; > > > > + u32 cookie; > > > > +}; > > > > +static struct psci_reset_param *psci_reset_params __ro_after_init; > > > > +static size_t num_psci_reset_params __ro_after_init; > > > > + > > > > static inline bool psci_has_ext_power_state(void) > > > > { > > > > return psci_cpu_suspend_feature & > > > > @@ -305,9 +313,38 @@ static int get_set_conduit_method(const struct device_node *np) > > > > return 0; > > > > } > > > > > > > > +static void psci_vendor_system_reset2(const char *cmd) > > > > +{ > > > > + unsigned long ret; > > > > + size_t i; > > > > + > > > > + for (i = 0; i < num_psci_reset_params; i++) { > > > > + if (!strcmp(psci_reset_params[i].mode, cmd)) { > > > > + ret = invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), > > > > + psci_reset_params[i].reset_type, > > > > + psci_reset_params[i].cookie, 0); > > > > + /* > > > > + * if vendor reset fails, log it and fall back to > > > > + * architecture reset types > > > > + */ > > > > + pr_err("failed to perform reset \"%s\": %ld\n", cmd, > > > > + (long)ret); > > > > + return; > > > > + } > > > > + } > > > > +} > > > > + > > > > static int psci_sys_reset(struct notifier_block *nb, unsigned long action, > > > > void *data) > > > > { > > > > + /* > > > > + * try to do the vendor system_reset2 > > > > + * If the reset fails or there wasn't a match on the command, > > > > + * fall back to architectural resets > > > > + */ > > > > + if (data && num_psci_reset_params) > > > > + psci_vendor_system_reset2(data); > > > > + > > > > if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) && > > > > psci_system_reset2_supported) { > > > > > > This is a mess. To issue architectural warm reset we check reboot_mode, > > > for vendor resets we ignore it - there is no rationale, that's the point > > > I am making. > > > > If I expand the comment to: > > > > > > * try todo the vendor system_reset2 > > * If the reset fails or there wasn't a match on the command, > > * fall back to architectural resets. > > * Ignore reboot_mode enum to behave like setting a cookie, which don't > > * care about the reboot_mode. > > /* > * Check if the system supports vendor resets and issue > * SYSTEM_RESET2 if the reboot command matches a vendor reset. > * Ignore reboot_mode and execute SYSTEM_RESET2 with type and > * cookie as defined by the firmware bindings. > * > * If the reset fails or there is not a match for the command > * fall back to architectural resets; reset type detection in > * this case will be done using reboot_mode. > */ > > ? > > > Help to address this concern? > > Not entirely, sorry, I will get back to this. > > > > Also see my question on the other thread re: user space and reset > > > "modes". > > > > > > I appreciate we are not making progress but I don't want to pick up > > > the pieces later after merging this code - it is unclear to me what's > > > the best path forward - I would like to understand how other > > > platforms/arches behave in this respect. > > > > > > > I went through the couple hundred drivers which register reboot and > > restart handlers. The majority don't care about reboot command nor > > reboot_mode enum. The few that do: > > > > Two drivers which I could find which care about the reboot command don't > > look at the reboot_mode argument. > > > > [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/firmware/efi/efibc.c?h=v6.11#n35 > > [2]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/power/reset/reboot-mode.c?h=v6.11#n42 > > > > One driver looks at the reboot command overrides the reboot_mode > > argument: > > > > [3]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/watchdog/pnx4008_wdt.c?h=v6.11#n125 > > Thanks for doing that, that helps. > > > I wasn't able to find any platform/arches which check the reboot_mode > > before reading the reboot command. > > > > > > /* > > > > @@ -750,6 +787,73 @@ static const struct of_device_id psci_of_match[] __initconst = { > > > > {}, > > > > }; > > > > > > > > +#define REBOOT_PREFIX "mode-" > > > > + > > > > +static int __init psci_init_system_reset2_modes(void) > > > > +{ > > > > + const size_t len = strlen(REBOOT_PREFIX); > > > > + struct psci_reset_param *param; > > > > + struct device_node *psci_np __free(device_node) = NULL; > > > > + struct device_node *np __free(device_node) = NULL; > > > > + struct property *prop; > > > > + size_t count = 0; > > > > + u32 magic[2]; > > > > + int num; > > > > + > > > > + if (!psci_system_reset2_supported) > > > > + return 0; > > > > + > > > > + psci_np = of_find_matching_node(NULL, psci_of_match); > > > > + if (!psci_np) > > > > + return 0; > > > > + > > > > + np = of_find_node_by_name(psci_np, "reset-types"); > > > > + if (!np) > > > > + return 0; > > > > + > > > > + for_each_property_of_node(np, prop) { > > > > + if (strncmp(prop->name, REBOOT_PREFIX, len)) > > > > + continue; > > > > + num = of_property_count_u32_elems(np, prop->name); > > > > + if (num != 1 && num != 2) > > > > + continue; > > > > + > > > > + count++; > > > > + } > > > > + > > > > + param = psci_reset_params = > > > > + kcalloc(count, sizeof(*psci_reset_params), GFP_KERNEL); > > > > + if (!psci_reset_params) > > > > + return -ENOMEM; > > > > + > > > > + for_each_property_of_node(np, prop) { > > > > + if (strncmp(prop->name, REBOOT_PREFIX, len)) > > > > + continue; > > > > + > > > > + param->mode = kstrdup_const(prop->name + len, GFP_KERNEL); > > > > > > FWIW - I think you need to keep the logic in the previous loop into account > > > because that's what is used to allocate param, it is not a given that > > > param is valid at this stage if I am not mistaken - the previous loop > > > checked: > > > > > > num = of_property_count_u32_elems(np, prop->name); > > > if (num != 1 && num != 2) > > > continue; > > > > of_property_read_variable_u32_array() performs effectively the same > > check. It returns -EOVERFLOW if it couldn't find enough (== 0) or too > > many values (>2). I currently have the added bonus of complaining in > > dmesg about the bad reboot mode property, instead of silently ignoring. > > Right but we are dereferencing param (param->mode) before carrying out that > check. > Ah, right, I see the problem. I'll send out another version after settling on the other part of the discussion! Thanks, Elliot