From: "Borislav Petkov (AMD)" bp@alien8.de
stable inclusion from stable-v5.10.189 commit 4acaea47e3bcb7cd55cc56c7fd4e5fb60eebdada category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7RQ67 CVE: CVE-2023-20569
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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Upstream commit: 233d6f68b98d480a7c42ebe78c38f79d44741ca9
Add the option to mitigate using IBPB on a kernel entry. Pull in the Retbleed alternative so that the IBPB call from there can be used. Also, if Retbleed mitigation is done using IBPB, the same mitigation can and must be used here.
Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Jialin Zhang zhangjialin11@huawei.com (cherry picked from commit a960084bb5d6804197483726e280e16f3e37aeda) Signed-off-by: Jialin Zhang zhangjialin11@huawei.com --- arch/x86/include/asm/nospec-branch.h | 3 ++- arch/x86/kernel/cpu/bugs.c | 23 +++++++++++++++++++++++ 2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 888256d2f1c6..d03fd4258aa9 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -173,7 +173,8 @@ * where we have a stack but before any RET instruction. */ .macro UNTRAIN_RET -#if defined(CONFIG_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_IBPB_ENTRY) +#if defined(CONFIG_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_IBPB_ENTRY) || \ + defined(CONFIG_CPU_SRSO) ANNOTATE_UNRET_END ALTERNATIVE_2 "", \ CALL_ZEN_UNTRAIN_RET, X86_FEATURE_UNRET, \ diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index f2a7d9491955..c6f6d5b98f4e 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2279,18 +2279,21 @@ enum srso_mitigation { SRSO_MITIGATION_NONE, SRSO_MITIGATION_MICROCODE, SRSO_MITIGATION_SAFE_RET, + SRSO_MITIGATION_IBPB, };
enum srso_mitigation_cmd { SRSO_CMD_OFF, SRSO_CMD_MICROCODE, SRSO_CMD_SAFE_RET, + SRSO_CMD_IBPB, };
static const char * const srso_strings[] = { [SRSO_MITIGATION_NONE] = "Vulnerable", [SRSO_MITIGATION_MICROCODE] = "Mitigation: microcode", [SRSO_MITIGATION_SAFE_RET] = "Mitigation: safe RET", + [SRSO_MITIGATION_IBPB] = "Mitigation: IBPB", };
static enum srso_mitigation srso_mitigation __ro_after_init = SRSO_MITIGATION_NONE; @@ -2307,6 +2310,8 @@ static int __init srso_parse_cmdline(char *str) srso_cmd = SRSO_CMD_MICROCODE; else if (!strcmp(str, "safe-ret")) srso_cmd = SRSO_CMD_SAFE_RET; + else if (!strcmp(str, "ibpb")) + srso_cmd = SRSO_CMD_IBPB; else pr_err("Ignoring unknown SRSO option (%s).", str);
@@ -2348,6 +2353,14 @@ static void __init srso_select_mitigation(void) setup_force_cpu_cap(X86_FEATURE_SRSO_NO); }
+ if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB) { + if (has_microcode) { + pr_err("Retbleed IBPB mitigation enabled, using same for SRSO\n"); + srso_mitigation = SRSO_MITIGATION_IBPB; + goto pred_cmd; + } + } + switch (srso_cmd) { case SRSO_CMD_OFF: return; @@ -2372,6 +2385,16 @@ static void __init srso_select_mitigation(void) } break;
+ case SRSO_CMD_IBPB: + if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) { + if (has_microcode) { + setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB); + srso_mitigation = SRSO_MITIGATION_IBPB; + } + } else { + pr_err("WARNING: kernel not compiled with CPU_IBPB_ENTRY.\n"); + goto pred_cmd; + } default: break; }