From: Thadeu Lima de Souza Cascardo cascardo@canonical.com
stable inclusion from stable-v5.10.133 commit 51552b6b52fc865f37ef3ddacd27d807a36695ac category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5PTAS CVE: CVE-2022-29900,CVE-2022-23816,CVE-2022-29901
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 2259da159fbe5dba8ac00b560cf00b6a6537fa18 upstream.
There are some VM configurations which have Skylake model but do not support IBPB. In those cases, when using retbleed=ibpb, userspace is going to be killed and kernel is going to panic.
If the CPU does not support IBPB, warn and proceed with the auto option. Also, do not fallback to IBPB on AMD/Hygon systems if it is not supported.
Fixes: 3ebc17006888 ("x86/bugs: Add retbleed=ibpb") Signed-off-by: Thadeu Lima de Souza Cascardo cascardo@canonical.com Signed-off-by: Borislav Petkov bp@suse.de Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Lin Yujun linyujun809@huawei.com Reviewed-by: Zhang Jianhua chris.zjh@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- arch/x86/kernel/cpu/bugs.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index e96d33675229..bb5a5069fad9 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -821,7 +821,10 @@ static void __init retbleed_select_mitigation(void) break;
case RETBLEED_CMD_IBPB: - if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) { + if (!boot_cpu_has(X86_FEATURE_IBPB)) { + pr_err("WARNING: CPU does not support IBPB.\n"); + goto do_cmd_auto; + } else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) { retbleed_mitigation = RETBLEED_MITIGATION_IBPB; } else { pr_err("WARNING: kernel not compiled with CPU_IBPB_ENTRY.\n"); @@ -836,7 +839,7 @@ static void __init retbleed_select_mitigation(void) boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { if (IS_ENABLED(CONFIG_CPU_UNRET_ENTRY)) retbleed_mitigation = RETBLEED_MITIGATION_UNRET; - else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) + else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY) && boot_cpu_has(X86_FEATURE_IBPB)) retbleed_mitigation = RETBLEED_MITIGATION_IBPB; }