rdpru in ubuntu_kvm_unit_tests failed on B-4.15 node riccioli with FAIL: RDPRU raises #UD

Test passed on this node with newer kernel (focal).

This hardware is an AMD system, codename Rome, Second generation Epyc

Fix:
https://github.com/torvalds/linux/commit/9d40b85bb46a99bc95dad3a07787da93b0a018e9
https://github.com/torvalds/linux/commit/0cb8410b90e78948984f35f2c4d50c2c0b7ee675

With patched kernel, the rdpru flag will be available in cpuinfo:
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid extd_apicid aperfmperf pni pclmulqdq monitor ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb cat_l3 cdp_l3 invpcid_single hw_pstate ssbd ibrs ibpb stibp vmmcall fsgsbase bmi1 avx2 smep bmi2 erms invpcid cqm rdt_a rdseed adx smap clflushopt clwb sha_ni xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local clzero irperf xsaveerptr rdpru arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold v_vmsave_vmload vgif umip pku ospke vaes vpclmulqdq rdpid overflow_recov succor smca
bugs : sysret_ss_attrs spectre_v1 spectre_v2 spec_store_bypass

$ sudo ./rdpru
BUILD_HEAD=16647354
timeout -k 1s --foreground 90s /usr/bin/qemu-system-x86_64 --no-reboot -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=kvm -kernel /tmp/tmp.syc17ecDpN -smp 1 -cpu max # -initrd /tmp/tmp.poLG53JqrJ
enabling apic
PASS: RDPRU raises #UD
SUMMARY: 1 tests
PASS rdpru (1 tests)

With kvm-unit-test repo updated to d8a4f9e5 (ci: Update the list of tests that we run in the Fedora Cirrus-CI), this test is still failing with the same error message.

This bug is awaiting verification that the linux/4.15.0-206.217 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-bionic' to 'verification-done-bionic'. If the problem still exists, change the tag 'verification-needed-bionic' to 'verification-failed-bionic'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

Verified on node riccioli with 4.15.0-206.217, this issue has gone.

This bug was fixed in the package linux - 4.15.0-206.217

---------------
linux (4.15.0-206.217) bionic; urgency=medium

  * bionic/linux: 4.15.0-206.217 -proposed tracker (LP: #2004655)

  * CVE-2023-0461
    - SAUCE: Fix inet_csk_listen_start after CVE-2023-0461

linux (4.15.0-205.216) bionic; urgency=medium

  * bionic/linux: 4.15.0-205.216 -proposed tracker (LP: #2004414)

  * Bionic update: upstream stable patchset 2023-01-20 (LP: #2003596)
    - NFSv4.1: Handle RECLAIM_COMPLETE trunking errors
    - NFSv4.1: We must always send RECLAIM_COMPLETE after a reboot
    - nfs4: Fix kmemleak when allocate slot failed
    - net: dsa: Fix possible memory leaks in dsa_loop_init()
    - nfc: s3fwrn5: Fix potential memory leak in s3fwrn5_nci_send()
    - nfc: nfcmrvl: Fix potential memory leak in nfcmrvl_i2c_nci_send()
    - net: fec: fix improper use of NETDEV_TX_BUSY
    - ata: pata_legacy: fix pdc20230_set_piomode()
    - net: sched: Fix use after free in red_enqueue()
    - ipvs: use explicitly signed chars
    - rose: Fix NULL pointer dereference in rose_send_frame()
    - mISDN: fix possible memory leak in mISDN_register_device()
    - isdn: mISDN: netjet: fix wrong check of device registration
    - btrfs: fix inode list leak during backref walking at resolve_indirect_refs()
    - btrfs: fix ulist leaks in error paths of qgroup self tests
    - Bluetooth: L2CAP: fix use-after-free in l2cap_conn_del()
    - net: mdio: fix undefined behavior in bit shift for __mdiobus_register
    - net, neigh: Fix null-ptr-deref in neigh_table_clear()
    - media: s5p_cec: limit msg.len to CEC_MAX_MSG_SIZE
    - media: dvb-frontends/drxk: initialize err to 0
    - i2c: xiic: Add platform module alias
    - Bluetooth: L2CAP: Fix attempting to access uninitialized memory
    - block, bfq: protect 'bfqd->queued' by 'bfqd->lock'
    - btrfs: fix type of parameter generation in btrfs_get_dentry
    - tcp/udp: Make early_demux back namespacified.
    - capabilities: fix potential memleak on error path from vfs_getxattr_alloc()
    - ALSA: usb-audio: Add quirks for MacroSilicon MS2100/MS2106 devices
    - efi: random: reduce seed size to 32 bytes
    - parisc: Make 8250_gsc driver dependend on CONFIG_PARISC
    - parisc: Export iosapic_serial_irq() symbol for serial port driver
    - ext4: fix warning in 'ext4_da_release_space'
    - KVM: x86: Mask off reserved bits in CPUID.80000008H
    - KVM: x86: emulator: em_sysexit should update ctxt->mode
    - KVM: x86: emulator: introduce emulator_recalc_and_set_mode
    - KVM: x86: emulator: update the emulation mode after CR0 write
    - linux/const.h: prefix include guard of uapi/linux/const.h with _UAPI
    - linux/const.h: move UL() macro to include/linux/const.h
    - linux/bits.h: make BIT(), GENMASK(), and friends available in assembly
    - RDMA/qedr: clean up work queue on failure in qedr_alloc_resources()
    - net: tun: fix bugs for oversize packet when napi frags enabled
    - ipvs: fix WARNING in __ip_vs_cleanup_batch()
    - ipvs: fix WARNING in ip_vs_app_net_cleanup()
    - ipv6: fix WARNING in ip6_route_net_exit_late()
    - parisc: Avoid printing the hardware path twice
    - HID: hyperv: fix possible memor...

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