<div dir="ltr"><div>Applied to bionic:linux master-next, thanks :)</div><div> </div><div>- Luke </div> <div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jan 16, 2023 at 9:52 PM Po-Hsu Lin <<a href="mailto:po-hsu.lin@canonical.com">po-hsu.lin@canonical.com</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">[Impact] RDPRU, the Read Processor Register instruction of AMD Zen 2 processors is used to give access to some processor registers that are typically only accessible when the privilege level is zero. rdpru test in ubuntu_kvm_unit_tests is to check if the RDPRU instruction can be intercepted by the Hypervisor. Without this patchset, this test will fail on our AMD Zen 2 system "riccioli" with: FAIL: RDPRU raises #UD [Fix] * fb64f293 x86/cpufeatures: Add feature bit RDPRU on AMD * 0cb8410b kvm: svm: Intercept RDPRU We have these patches in newer releases already, only Bionic 4.15 requires this fix. The first patch needs to be backported with some context adjustment, the second can be cherry-picked. [Test] Test kernel can be found here: <a href="https://people.canonical.com/~phlin/kernel/lp-1968681-rdpru/" rel="noreferrer" target="_blank">https://people.canonical.com/~phlin/kernel/lp-1968681-rdpru/</a> With the patched kernel, this rdpru test will pass on the target AMD Zen 2 system. $ sudo ./rdpru BUILD_HEAD=d6421940 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.XOMVxpyNnl -smp 1 -cpu max # -initrd /tmp/tmp.I2TbGXFiaZ enabling apic smp: waiting for 0 APs PASS: RDPRU raises #UD SUMMARY: 1 tests PASS rdpru (1 tests) And the rdpru flag will be available in cpuinfo: $ grep -o rdpru /proc/cpuinfo rdpru [Where problems could occur] This patchset will add a new feature bit RDPRU for AMD Zen 2. We can expect to see new issues coming up when using this bit in the future. Babu Moger (1): x86/cpufeatures: Add feature bit RDPRU on AMD Jim Mattson (1): kvm: svm: Intercept RDPRU arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/svm.h | 1 + arch/x86/include/uapi/asm/svm.h | 1 + arch/x86/kvm/svm.c | 8 ++++++++ 4 files changed, 11 insertions(+) -- 2.7.4 -- kernel-team mailing list <a href="mailto:kernel-team@lists.ubuntu.com" target="_blank">kernel-team@lists.ubuntu.com</a> <a href="https://lists.ubuntu.com/mailman/listinfo/kernel-team" rel="noreferrer" target="_blank">https://lists.ubuntu.com/mailman/listinfo/kernel-team</a> </blockquote></div></div>