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hw/ppc: Preserve memory regions registered for fadump
While the first kernel boots, it registers memory regions for fadump
such as:
* CPU state data (has to be populated by the platform)
* HPTE state data (has to be populated by the platform)
* Real Mode Regions (platform should copy it to requested
destination addresses)
* OS defined regions (such as parameter save area)
Platform is also expected to modify the 'bytes_dumped' to the length of
data preserved/copied by platform (ideally same as the source length
passed by kernel).
The kernel passes source address and length for the memory regions, and
a destination address to where the memory is to be copied.
Implement the preserving/copying of the Real Mode Regions and the
Parameter Save Area in QEMU Pseries
The regions are copied in chunks instead of copying all at once.
Signed-off-by: Aditya Gupta <adityag@linux.ibm.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Tested-by: Shivang Upadhyay <shivangu@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20251021134823.1861675-4-adityag@linux.ibm.com
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
This commit is contained in:
Aditya Gupta
+179
-6
@@ -7,7 +7,9 @@
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#include "qemu/osdep.h"
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#include "qemu/log.h"
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#include "hw/ppc/spapr.h"
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#include "qemu/units.h"
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#include "system/cpus.h"
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#include <math.h>
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/*
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* Handle the "FADUMP_CMD_REGISTER" command in 'ibm,configure-kernel-dump'
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@@ -123,14 +125,185 @@ uint32_t do_fadump_register(SpaprMachineState *spapr, target_ulong args)
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return RTAS_OUT_SUCCESS;
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}
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/* Preserve the memory locations registered for fadump */
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static bool fadump_preserve_mem(void)
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/*
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* Copy the source region of given fadump section, to the destination
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* address mentioned in the region
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*
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* Also set the region's error flag, if the copy fails due to non-existent
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* address (MEMTX_DECODE_ERROR) or permission issues (MEMTX_ACCESS_ERROR)
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*
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* Returns true if successful copy
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*
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* Returns false in case of any other error, being treated as hardware
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* error for fadump purposes
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*/
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static bool do_preserve_region(FadumpSection *region)
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{
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AddressSpace *default_as = &address_space_memory;
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MemTxResult io_result;
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MemTxAttrs attrs;
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uint64_t src_addr, src_len, dest_addr;
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uint64_t num_chunks;
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g_autofree void *copy_buffer = NULL;
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src_addr = be64_to_cpu(region->source_address);
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src_len = be64_to_cpu(region->source_len);
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dest_addr = be64_to_cpu(region->destination_address);
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/* Mark the memory transaction as privileged memory access */
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attrs.user = 0;
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attrs.memory = 1;
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/*
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* TODO: Implement preserving memory regions requested during fadump
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* registration
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* Optimisation: Skip copy if source and destination are same
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* (eg. param area)
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*/
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return false;
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if (src_addr == dest_addr) {
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region->bytes_dumped = cpu_to_be64(src_len);
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return true;
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}
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#define FADUMP_CHUNK_SIZE ((size_t)(32 * MiB))
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copy_buffer = g_try_malloc(FADUMP_CHUNK_SIZE);
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if (copy_buffer == NULL) {
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qemu_log_mask(LOG_GUEST_ERROR,
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"FADump: Failed allocating memory (size: %zu) for copying"
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" reserved memory regions\n", FADUMP_CHUNK_SIZE);
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}
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num_chunks = ceil((src_len * 1.0f) / FADUMP_CHUNK_SIZE);
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for (uint64_t chunk_id = 0; chunk_id < num_chunks; ++chunk_id) {
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/* Take minimum of bytes left to copy, and chunk size */
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uint64_t copy_len = MIN(
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src_len - (chunk_id * FADUMP_CHUNK_SIZE),
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FADUMP_CHUNK_SIZE
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);
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/* Copy the source region to destination */
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io_result = address_space_read(default_as, src_addr, attrs,
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copy_buffer, copy_len);
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if ((io_result & MEMTX_DECODE_ERROR) ||
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(io_result & MEMTX_ACCESS_ERROR)) {
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qemu_log_mask(LOG_GUEST_ERROR,
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"FADump: Failed to decode/access address in section: %d\n",
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region->source_data_type);
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/*
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* Invalid source address is not an hardware error, instead
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* wrong parameter from the kernel.
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* Return true to let caller know to continue reading other
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* sections
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*/
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region->error_flags = FADUMP_ERROR_INVALID_SOURCE_ADDR;
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region->bytes_dumped = 0;
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return true;
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} else if (io_result != MEMTX_OK) {
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qemu_log_mask(LOG_GUEST_ERROR,
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"FADump: Failed to read source region in section: %d\n",
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region->source_data_type);
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return false;
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}
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io_result = address_space_write(default_as, dest_addr, attrs,
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copy_buffer, copy_len);
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if ((io_result & MEMTX_DECODE_ERROR) ||
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(io_result & MEMTX_ACCESS_ERROR)) {
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qemu_log_mask(LOG_GUEST_ERROR,
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"FADump: Failed to decode/access address in section: %d\n",
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region->source_data_type);
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/*
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* Invalid destination address is not an hardware error,
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* instead wrong parameter from the kernel.
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* Return true to let caller know to continue reading other
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* sections
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*/
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region->error_flags = FADUMP_ERROR_INVALID_DEST_ADDR;
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region->bytes_dumped = 0;
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return true;
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} else if (io_result != MEMTX_OK) {
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qemu_log_mask(LOG_GUEST_ERROR,
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"FADump: Failed to write destination in section: %d\n",
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region->source_data_type);
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return false;
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}
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src_addr += FADUMP_CHUNK_SIZE;
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dest_addr += FADUMP_CHUNK_SIZE;
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}
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#undef FADUMP_CHUNK_SIZE
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/*
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* Considering address_space_write would have copied the
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* complete region
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*/
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region->bytes_dumped = cpu_to_be64(src_len);
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return true;
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}
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/* Preserve the memory locations registered for fadump */
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static bool fadump_preserve_mem(SpaprMachineState *spapr)
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{
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FadumpMemStruct *fdm = &spapr->registered_fdm;
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uint16_t dump_num_sections, data_type;
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assert(spapr->fadump_registered);
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/*
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* Handle all sections
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*
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* CPU State Data and HPTE regions are handled in their own cases
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*
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* RMR regions and any custom OS reserved regions such as parameter
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* save area, are handled by simply copying the source region to
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* destination address
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*/
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dump_num_sections = be16_to_cpu(fdm->header.dump_num_sections);
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for (int i = 0; i < dump_num_sections; ++i) {
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data_type = be16_to_cpu(fdm->rgn[i].source_data_type);
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/* Reset error_flags & bytes_dumped for now */
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fdm->rgn[i].error_flags = 0;
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fdm->rgn[i].bytes_dumped = 0;
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/* If kernel did not request for the memory region, then skip it */
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if (be32_to_cpu(fdm->rgn[i].request_flag) != FADUMP_REQUEST_FLAG) {
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qemu_log_mask(LOG_UNIMP,
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"FADump: Skipping copying region as not requested\n");
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continue;
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}
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switch (data_type) {
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case FADUMP_CPU_STATE_DATA:
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/* TODO: Add CPU state data */
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break;
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case FADUMP_HPTE_REGION:
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/* TODO: Add hpte state data */
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break;
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case FADUMP_REAL_MODE_REGION:
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case FADUMP_PARAM_AREA:
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/* Copy the memory region from region's source to its destination */
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if (!do_preserve_region(&fdm->rgn[i])) {
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qemu_log_mask(LOG_GUEST_ERROR,
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"FADump: Failed to preserve dump section: %d\n",
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be16_to_cpu(fdm->rgn[i].source_data_type));
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fdm->header.dump_status_flag |=
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cpu_to_be16(FADUMP_STATUS_DUMP_ERROR);
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}
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break;
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default:
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qemu_log_mask(LOG_GUEST_ERROR,
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"FADump: Skipping unknown source data type: %d\n", data_type);
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fdm->rgn[i].error_flags =
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cpu_to_be16(FADUMP_ERROR_INVALID_DATA_TYPE);
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}
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}
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return true;
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}
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/*
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@@ -151,7 +324,7 @@ void trigger_fadump_boot(SpaprMachineState *spapr, target_ulong spapr_retcode)
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pause_all_vcpus();
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/* Preserve the memory locations registered for fadump */
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if (!fadump_preserve_mem()) {
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if (!fadump_preserve_mem(spapr)) {
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/* Failed to preserve the registered memory regions */
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rtas_st(spapr_retcode, 0, RTAS_OUT_HW_ERROR);
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@@ -16,11 +16,29 @@
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#define FADUMP_VERSION 1
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/* Firmware provided dump sections */
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#define FADUMP_CPU_STATE_DATA 0x0001
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#define FADUMP_HPTE_REGION 0x0002
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#define FADUMP_REAL_MODE_REGION 0x0011
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/* OS defined sections */
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#define FADUMP_PARAM_AREA 0x0100
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/* Dump request flag */
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#define FADUMP_REQUEST_FLAG 0x00000001
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/* Dump status flags */
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#define FADUMP_STATUS_DUMP_PERFORMED 0x8000
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#define FADUMP_STATUS_DUMP_TRIGGERED 0x4000
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#define FADUMP_STATUS_DUMP_ERROR 0x2000
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/* Region dump error flags */
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#define FADUMP_ERROR_INVALID_DATA_TYPE 0x8000
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#define FADUMP_ERROR_INVALID_SOURCE_ADDR 0x4000
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#define FADUMP_ERROR_LENGTH_EXCEEDS_SOURCE 0x2000
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#define FADUMP_ERROR_INVALID_DEST_ADDR 0x1000
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#define FAUDMP_ERROR_DEST_TOO_SMALL 0x0800
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/*
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* The Firmware Assisted Dump Memory structure supports a maximum of 10 sections
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* in the dump memory structure. Presently, three sections are used for
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