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Fri, 17 Oct 2025 11:26:08 +0000 (GMT) Message-ID: <0dda0c58-0351-41a6-bc76-56e46aa8f02c@linux.ibm.com> Date: Fri, 17 Oct 2025 16:56:07 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 3/8] hw/ppc: Trigger Fadump boot if fadump is registered To: Aditya Gupta , qemu-devel@nongnu.org Cc: qemu-ppc@nongnu.org, Nicholas Piggin , Daniel Henrique Barboza , Harsh Prateek Bora , Mahesh J Salgaonkar , Hari Bathini References: <20250323174007.221116-1-adityag@linux.ibm.com> <20250323174007.221116-4-adityag@linux.ibm.com> Content-Language: en-US From: Sourabh Jain In-Reply-To: <20250323174007.221116-4-adityag@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: k8Jg8XxZXfD7M5gHrBeDMa--TtBvjnyZ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDE1MDEyNSBTYWx0ZWRfXxwSCZU/ixwOz kW37vd1hXkiMkXWa/sqlE9G527a4nuMkleOhB1c5wEOnzCjd9K/CViWAs8bqSxJQKnd4Mbbijh+ 6DVK+FJOPuBUS1g+13nIrtZmdRE0nShvkzHEz/sH/8Fc4lRMznL20AnEgM9Ld+6oR7HchxVSd5Q musZ5yWM1oXgYwuS6rYKNbv+PaKpLJUZmZjEN0/gPIBMEUKxb/WJr17pcoROf3oWSvBkhGjasWV 0ojdMh3T3VdhX2UZ8pOIwgrWleRTJyGMiio+/Uz2rTejvDlaaUbu1mnDtK+ZJaXdT2n9DxVrQAO lQ3tRXAkUNnOP2gVgEGNWzO0o2qa2NeqBq4kQ1uzSGH8hpIsTHQD3XQ35zUfuKAFerAenYAoefL YbFLQEH9BzPyzn73PHxXdp4I7l7A8Q== X-Authority-Analysis: v=2.4 cv=R+wO2NRX c=1 sm=1 tr=0 ts=68f22bf1 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=x6icFKpwvdMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=WzUm8aunDAuTTI20kp8A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: A9Yf68WieKyujySKBAnWFjEtLLj6BA7j X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-17_04,2025-10-13_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 lowpriorityscore=0 suspectscore=0 bulkscore=0 clxscore=1015 priorityscore=1501 adultscore=0 spamscore=0 impostorscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510150125 Received-SPF: pass client-ip=148.163.158.5; envelope-from=sourabhjain@linux.ibm.com; helo=mx0b-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, T_SPF_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Fri, 17 Oct 2025 09:13:21 -0400 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 23/03/25 23:10, Aditya Gupta wrote: > According to PAPR: > > R1–7.3.30–3. When the platform receives an ibm,os-term RTAS call, or > on a system reset without an ibm,nmi-interlock RTAS call, if the > platform has a dump structure registered through the > ibm,configure-kernel-dump call, the platform must process each > registered kernel dump section as required and, when available, > present the dump structure information to the operating system > through the “ibm,kernel-dump” property, updated with status for each > dump section, until the dump has been invalidated through the > ibm,configure-kernel-dump RTAS call. > > If Fadump has been registered, trigger an Fadump boot (memory preserving > boot), if QEMU recieves a 'ibm,os-term' rtas call. > > Implementing the fadump boot as: > * pause all vcpus (will need to save registers later) > * preserve memory regions specified by fadump (will be implemented > in future) > * do a memory preserving reboot (GUEST_RESET in QEMU doesn't clear > the memory) > > Memory regions registered by fadump will be handled in a later patch. > > Note: Preserving memory regions is not implemented yet so on an > "ibm,os-term" call will just trigger a reboot in QEMU if fadump is > registered, and the second kernel will boot as a normal boot (not > fadump boot) > > Signed-off-by: Aditya Gupta > --- > hw/ppc/spapr_fadump.c | 77 +++++++++++++++++++++++++++++++++++ > hw/ppc/spapr_rtas.c | 5 +++ > include/hw/ppc/spapr_fadump.h | 6 +++ > 3 files changed, 88 insertions(+) > > diff --git a/hw/ppc/spapr_fadump.c b/hw/ppc/spapr_fadump.c > index 9c7fb9e12b16..fedd2cde9a4f 100644 > --- a/hw/ppc/spapr_fadump.c > +++ b/hw/ppc/spapr_fadump.c > @@ -7,6 +7,7 @@ > #include "qemu/osdep.h" > #include "qemu/log.h" > #include "hw/ppc/spapr.h" > +#include "system/cpus.h" > > /* > * Handle the "FADUMP_CMD_REGISTER" command in 'ibm,configure-kernel-dump' > @@ -121,3 +122,79 @@ uint32_t do_fadump_register(SpaprMachineState *spapr, target_ulong args) > > return RTAS_OUT_SUCCESS; > } > + > +/* Preserve the memory locations registered for fadump */ > +static bool fadump_preserve_mem(void) > +{ > + /* > + * TODO: Implement preserving memory regions requested during fadump > + * registration > + */ > + return false; > +} > + > +/* > + * Trigger a fadump boot, ie. next boot will be a crashkernel/fadump boot > + * with fadump dump active. > + * > + * This is triggered by ibm,os-term RTAS call, if fadump was registered. > + * > + * It preserves the memory and sets 'FADUMP_STATUS_DUMP_TRIGGERED' as > + * fadump status, which can be used later to add the "ibm,kernel-dump" > + * device tree node as presence of 'FADUMP_STATUS_DUMP_TRIGGERED' signifies > + * next boot as fadump boot in our case > + */ > +void trigger_fadump_boot(SpaprMachineState *spapr, target_ulong spapr_retcode) > +{ > + FadumpSectionHeader *header = &spapr->registered_fdm.header; > + > + pause_all_vcpus(); > + > + /* Preserve the memory locations registered for fadump */ > + if (!fadump_preserve_mem()) { > + /* Failed to preserve the registered memory regions */ > + rtas_st(spapr_retcode, 0, RTAS_OUT_HW_ERROR); > + > + /* Cause a reboot */ > + qemu_system_guest_panicked(NULL); > + return; > + } > + > + /* > + * Mark next boot as fadump boot > + * > + * Note: These is some bit of assumption involved here, as PAPR doesn't > + * specify any use of the dump status flags, nor does the kernel use it > + * > + * But from description in Table 136 in PAPR v2.13, it looks like: > + * FADUMP_STATUS_DUMP_TRIGGERED > + * = Dump was triggered by the previous system boot (PAPR says) > + * = Next boot will be a fadump boot (My perception) Can we say assumption made or assumed instead of My perception. > + * > + * FADUMP_STATUS_DUMP_PERFORMED > + * = Dump performed (Set to 0 by caller of the > + * ibm,configure-kernel-dump call) (PAPR says) > + * = Firmware has performed the copying/dump of requested regions > + * (My perception) > + * = Dump is active for the next boot (My perception) Same here. > + */ > + header->dump_status_flag = cpu_to_be16( > + FADUMP_STATUS_DUMP_TRIGGERED | /* Next boot will be fadump boot */ > + FADUMP_STATUS_DUMP_PERFORMED /* Dump is active */ > + ); > + > + /* Reset fadump_registered for next boot */ > + spapr->fadump_registered = false; > + spapr->fadump_dump_active = true; > + > + /* > + * Then do a guest reset > + * > + * Requirement: > + * GUEST_RESET is expected to NOT clear the memory, as is the case when > + * this is merged > + */ > + qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET); > + > + rtas_st(spapr_retcode, 0, RTAS_OUT_SUCCESS); > +} > diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c > index 0454938a01e9..14b954a05109 100644 > --- a/hw/ppc/spapr_rtas.c > +++ b/hw/ppc/spapr_rtas.c > @@ -412,6 +412,11 @@ static void rtas_ibm_os_term(PowerPCCPU *cpu, > target_ulong msgaddr = rtas_ld(args, 0); > char msg[512]; > > + if (spapr->fadump_registered) { > + /* If fadump boot works, control won't come back here */ > + return trigger_fadump_boot(spapr, rets); > + } > + > cpu_physical_memory_read(msgaddr, msg, sizeof(msg) - 1); > msg[sizeof(msg) - 1] = 0; > > diff --git a/include/hw/ppc/spapr_fadump.h b/include/hw/ppc/spapr_fadump.h > index 6abbcb44f353..e484604c1c70 100644 > --- a/include/hw/ppc/spapr_fadump.h > +++ b/include/hw/ppc/spapr_fadump.h > @@ -16,6 +16,11 @@ > > #define FADUMP_VERSION 1 > > +/* Dump status flags */ > +#define FADUMP_STATUS_DUMP_PERFORMED 0x8000 > +#define FADUMP_STATUS_DUMP_TRIGGERED 0x4000 > +#define FADUMP_STATUS_DUMP_ERROR 0x2000 > + > /* > * The Firmware Assisted Dump Memory structure supports a maximum of 10 sections > * in the dump memory structure. Presently, three sections are used for > @@ -66,4 +71,5 @@ struct FadumpMemStruct { > }; > > uint32_t do_fadump_register(struct SpaprMachineState *, target_ulong); > +void trigger_fadump_boot(struct SpaprMachineState *, target_ulong); > #endif /* PPC_SPAPR_FADUMP_H */