perf/x86/amd/core: Avoid enabling BRS from the SVM reload path
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Linux | Linux | affected |
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| Source | ID | Title |
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Ubuntu USN |
USN-8887-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8888-1 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-8889-1 | Linux kernel (OEM) vulnerabilities |
Ubuntu USN |
USN-8887-2 | Linux kernel (AWS) vulnerabilities |
Ubuntu USN |
USN-8888-2 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-8887-3 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8917-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8918-1 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-9003-1 | Linux kernel (NVIDIA) vulnerabilities |
Ubuntu USN |
USN-9024-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-9025-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-9026-1 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-9040-1 | Linux kernel (Low Latency NVIDIA) vulnerabilities |
Ubuntu USN |
USN-9043-1 | Linux kernel (NVIDIA) vulnerabilities |
Ubuntu USN |
USN-9066-1 | Linux kernel (HWE) vulnerabilities |
Ubuntu USN |
USN-9091-1 | Linux kernel (NVIDIA Tegra) vulnerabilities |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.223% probability within 30 days)
Key SSVC decision points have not yet been added.
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| Weaknesses | CWE-665 |
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| Weaknesses | CWE-358 | |
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cvssV3_1
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| Weaknesses | CWE-665 |
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| Description | In the Linux kernel, the following vulnerability has been resolved: perf/x86/amd/core: Avoid enabling BRS from the SVM reload path Branch Sampling (BRS) and Last Branch Record (LBR) are mutually exclusive hardware features, and users of both are tracked via cpuc->lbr_users. When SVM is toggled on a CPU, the host perf events are reprogrammed to update the HostOnly filter bit (set when virtualization is enabled, cleared when it is disabled). On PerfMonV2-capable processors, this reprogramming is performed by calling amd_pmu_enable_all() to rewrite the event selectors. However, amd_pmu_enable_all() also calls amd_brs_enable_all(), which enables BRS whenever cpuc->lbr_users > 0. Having active LBR events satisfies this gating on processors that have LBR but not BRS. The kernel then tries to set the BRS enable bit in DebugExtnCfg (MSR 0xc000010f). Since that bit is deprecated on such hardware, the write results in a #GP: Call Trace: <IRQ> amd_pmu_enable_all+0x1d/0x90 amd_pmu_disable_virt+0x62/0xb0 kvm_arch_disable_virtualization_cpu+0xa/0x40 [kvm] hardware_disable_nolock+0x1a/0x30 [kvm] __flush_smp_call_function_queue+0x9b/0x410 __sysvec_call_function+0x18/0xc0 sysvec_call_function+0x69/0x90 </IRQ> <TASK> asm_sysvec_call_function+0x16/0x20 RIP: 0010:cpuidle_enter_state+0xc4/0x450 ? cpuidle_enter_state+0xb7/0x450 cpuidle_enter+0x29/0x40 cpuidle_idle_call+0xf5/0x160 do_idle+0x7b/0xe0 cpu_startup_entry+0x26/0x30 start_secondary+0x115/0x140 secondary_startup_64_no_verify+0x194/0x19b </TASK> Fix this by ensuring that BRS is not enabled from the event selector reprogramming path even when cpuc->lbr_users > 0. | |
| Title | perf/x86/amd/core: Avoid enabling BRS from the SVM reload path | |
| First Time appeared |
Linux
Linux linux Kernel |
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| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
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| References |
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