From e2c2910edf90186ca0d7d13c9943caa284e95ea9 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Tue, 25 Apr 2023 21:15:14 -0400 Subject: [PATCH 51/56] migration: Allow postcopy_ram_supported_by_host() to report err MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Peter Xu RH-MergeRequest: 162: migration: Pretty failures for postcopy on unsupported memory types RH-Bugzilla: 2057267 RH-Acked-by: Leonardo Brás RH-Acked-by: Miroslav Rezanina RH-Acked-by: quintela1 RH-Commit: [50/50] 08c44affc11c27ddf1aa7ce0dfacbaf5effb80cb (peterx/qemu-kvm) Instead of print it to STDERR, bring the error upwards so that it can be reported via QMP responses. E.g.: { "execute": "migrate-set-capabilities" , "arguments": { "capabilities": [ { "capability": "postcopy-ram", "state": true } ] } } { "error": { "class": "GenericError", "desc": "Postcopy is not supported: Host backend files need to be TMPFS or HUGETLBFS only" } } Signed-off-by: Peter Xu Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela (cherry picked from commit 74c38cf7fd24c60e4f0a90585d17250478260877) Signed-off-by: Peter Xu --- migration/options.c | 8 ++---- migration/postcopy-ram.c | 60 +++++++++++++++++++++------------------- migration/postcopy-ram.h | 3 +- migration/savevm.c | 3 +- 4 files changed, 39 insertions(+), 35 deletions(-) diff --git a/migration/options.c b/migration/options.c index 4701c75a4d..e51d667e14 100644 --- a/migration/options.c +++ b/migration/options.c @@ -302,6 +302,7 @@ bool migrate_caps_check(bool *old_caps, bool *new_caps, Error **errp) { MigrationIncomingState *mis = migration_incoming_get_current(); + ERRP_GUARD(); #ifndef CONFIG_LIVE_BLOCK_MIGRATION if (new_caps[MIGRATION_CAPABILITY_BLOCK]) { error_setg(errp, "QEMU compiled without old-style (blk/-b, inc/-i) " @@ -327,11 +328,8 @@ bool migrate_caps_check(bool *old_caps, bool *new_caps, Error **errp) */ if (!old_caps[MIGRATION_CAPABILITY_POSTCOPY_RAM] && runstate_check(RUN_STATE_INMIGRATE) && - !postcopy_ram_supported_by_host(mis)) { - /* postcopy_ram_supported_by_host will have emitted a more - * detailed message - */ - error_setg(errp, "Postcopy is not supported"); + !postcopy_ram_supported_by_host(mis, errp)) { + error_prepend(errp, "Postcopy is not supported: "); return false; } diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index 0711500036..75aa276bb1 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -283,11 +283,13 @@ static bool request_ufd_features(int ufd, uint64_t features) return true; } -static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis) +static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis, + Error **errp) { uint64_t asked_features = 0; static uint64_t supported_features; + ERRP_GUARD(); /* * it's not possible to * request UFFD_API twice per one fd @@ -295,7 +297,7 @@ static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis) */ if (!supported_features) { if (!receive_ufd_features(&supported_features)) { - error_report("%s failed", __func__); + error_setg(errp, "Userfault feature detection failed"); return false; } } @@ -317,8 +319,7 @@ static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis) * userfault file descriptor */ if (!request_ufd_features(ufd, asked_features)) { - error_report("%s failed: features %" PRIu64, __func__, - asked_features); + error_setg(errp, "Failed features %" PRIu64, asked_features); return false; } @@ -329,7 +330,8 @@ static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis) have_hp = supported_features & UFFD_FEATURE_MISSING_HUGETLBFS; #endif if (!have_hp) { - error_report("Userfault on this host does not support huge pages"); + error_setg(errp, + "Userfault on this host does not support huge pages"); return false; } } @@ -338,7 +340,7 @@ static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis) /* Callback from postcopy_ram_supported_by_host block iterator. */ -static int test_ramblock_postcopiable(RAMBlock *rb) +static int test_ramblock_postcopiable(RAMBlock *rb, Error **errp) { const char *block_name = qemu_ram_get_idstr(rb); ram_addr_t length = qemu_ram_get_used_length(rb); @@ -346,16 +348,18 @@ static int test_ramblock_postcopiable(RAMBlock *rb) QemuFsType fs; if (length % pagesize) { - error_report("Postcopy requires RAM blocks to be a page size multiple," - " block %s is 0x" RAM_ADDR_FMT " bytes with a " - "page size of 0x%zx", block_name, length, pagesize); + error_setg(errp, + "Postcopy requires RAM blocks to be a page size multiple," + " block %s is 0x" RAM_ADDR_FMT " bytes with a " + "page size of 0x%zx", block_name, length, pagesize); return 1; } if (rb->fd >= 0) { fs = qemu_fd_getfs(rb->fd); if (fs != QEMU_FS_TYPE_TMPFS && fs != QEMU_FS_TYPE_HUGETLBFS) { - error_report("Host backend files need to be TMPFS or HUGETLBFS only"); + error_setg(errp, + "Host backend files need to be TMPFS or HUGETLBFS only"); return 1; } } @@ -368,7 +372,7 @@ static int test_ramblock_postcopiable(RAMBlock *rb) * normally fine since if the postcopy succeeds it gets turned back on at the * end. */ -bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) +bool postcopy_ram_supported_by_host(MigrationIncomingState *mis, Error **errp) { long pagesize = qemu_real_host_page_size(); int ufd = -1; @@ -377,29 +381,27 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) struct uffdio_register reg_struct; struct uffdio_range range_struct; uint64_t feature_mask; - Error *local_err = NULL; RAMBlock *block; + ERRP_GUARD(); if (qemu_target_page_size() > pagesize) { - error_report("Target page size bigger than host page size"); + error_setg(errp, "Target page size bigger than host page size"); goto out; } ufd = uffd_open(O_CLOEXEC); if (ufd == -1) { - error_report("%s: userfaultfd not available: %s", __func__, - strerror(errno)); + error_setg(errp, "Userfaultfd not available: %s", strerror(errno)); goto out; } /* Give devices a chance to object */ - if (postcopy_notify(POSTCOPY_NOTIFY_PROBE, &local_err)) { - error_report_err(local_err); + if (postcopy_notify(POSTCOPY_NOTIFY_PROBE, errp)) { goto out; } /* Version and features check */ - if (!ufd_check_and_apply(ufd, mis)) { + if (!ufd_check_and_apply(ufd, mis, errp)) { goto out; } @@ -417,7 +419,7 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) * affect in reality, or we can revisit. */ RAMBLOCK_FOREACH(block) { - if (test_ramblock_postcopiable(block)) { + if (test_ramblock_postcopiable(block, errp)) { goto out; } } @@ -427,7 +429,7 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) * it was enabled. */ if (munlockall()) { - error_report("%s: munlockall: %s", __func__, strerror(errno)); + error_setg(errp, "munlockall() failed: %s", strerror(errno)); goto out; } @@ -439,8 +441,7 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) testarea = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (testarea == MAP_FAILED) { - error_report("%s: Failed to map test area: %s", __func__, - strerror(errno)); + error_setg(errp, "Failed to map test area: %s", strerror(errno)); goto out; } g_assert(QEMU_PTR_IS_ALIGNED(testarea, pagesize)); @@ -450,14 +451,14 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING; if (ioctl(ufd, UFFDIO_REGISTER, ®_struct)) { - error_report("%s userfault register: %s", __func__, strerror(errno)); + error_setg(errp, "UFFDIO_REGISTER failed: %s", strerror(errno)); goto out; } range_struct.start = (uintptr_t)testarea; range_struct.len = pagesize; if (ioctl(ufd, UFFDIO_UNREGISTER, &range_struct)) { - error_report("%s userfault unregister: %s", __func__, strerror(errno)); + error_setg(errp, "UFFDIO_UNREGISTER failed: %s", strerror(errno)); goto out; } @@ -465,8 +466,8 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) (__u64)1 << _UFFDIO_COPY | (__u64)1 << _UFFDIO_ZEROPAGE; if ((reg_struct.ioctls & feature_mask) != feature_mask) { - error_report("Missing userfault map features: %" PRIx64, - (uint64_t)(~reg_struct.ioctls & feature_mask)); + error_setg(errp, "Missing userfault map features: %" PRIx64, + (uint64_t)(~reg_struct.ioctls & feature_mask)); goto out; } @@ -1188,6 +1189,8 @@ static int postcopy_temp_pages_setup(MigrationIncomingState *mis) int postcopy_ram_incoming_setup(MigrationIncomingState *mis) { + Error *local_err = NULL; + /* Open the fd for the kernel to give us userfaults */ mis->userfault_fd = uffd_open(O_CLOEXEC | O_NONBLOCK); if (mis->userfault_fd == -1) { @@ -1200,7 +1203,8 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis) * Although the host check already tested the API, we need to * do the check again as an ABI handshake on the new fd. */ - if (!ufd_check_and_apply(mis->userfault_fd, mis)) { + if (!ufd_check_and_apply(mis->userfault_fd, mis, &local_err)) { + error_report_err(local_err); return -1; } @@ -1360,7 +1364,7 @@ void fill_destination_postcopy_migration_info(MigrationInfo *info) { } -bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) +bool postcopy_ram_supported_by_host(MigrationIncomingState *mis, Error **errp) { error_report("%s: No OS support", __func__); return false; diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h index b4867a32d5..442ab89752 100644 --- a/migration/postcopy-ram.h +++ b/migration/postcopy-ram.h @@ -14,7 +14,8 @@ #define QEMU_POSTCOPY_RAM_H /* Return true if the host supports everything we need to do postcopy-ram */ -bool postcopy_ram_supported_by_host(MigrationIncomingState *mis); +bool postcopy_ram_supported_by_host(MigrationIncomingState *mis, + Error **errp); /* * Make all of RAM sensitive to accesses to areas that haven't yet been written diff --git a/migration/savevm.c b/migration/savevm.c index 9671211339..211eff3a8b 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -1753,7 +1753,8 @@ static int loadvm_postcopy_handle_advise(MigrationIncomingState *mis, return -EINVAL; } - if (!postcopy_ram_supported_by_host(mis)) { + if (!postcopy_ram_supported_by_host(mis, &local_err)) { + error_report_err(local_err); postcopy_state_set(POSTCOPY_INCOMING_NONE); return -1; } -- 2.39.1