x86/bugs: Report AMD retbleed vulnerability

commit 6b80b59b3555706508008f1f127b5412c89c7fd8 upstream.

Report that AMD x86 CPUs are vulnerable to the RETBleed (Arbitrary
Speculative Code Execution with Return Instructions) attack.

  [peterz: add hygon]
  [kim: invert parity; fam15h]

Co-developed-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index b7218d5..7f1fb9a 100644 (file)
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -443,5 +443,6 @@
 #define X86_BUG_ITLB_MULTIHIT          X86_BUG(23) /* CPU may incur MCE during certain page attribute changes */
 #define X86_BUG_SRBDS                  X86_BUG(24) /* CPU may leak RNG bits if not mitigated */
 #define X86_BUG_MMIO_STALE_DATA                X86_BUG(25) /* CPU is affected by Processor MMIO Stale Data vulnerabilities */
+#define X86_BUG_RETBLEED               X86_BUG(26) /* CPU is affected by RETBleed */
 
 #endif /* _ASM_X86_CPUFEATURES_H */

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 2c512ff..c62ea37 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1987,6 +1987,11 @@ static ssize_t srbds_show_state(char *buf)
        return sprintf(buf, "%s\n", srbds_strings[srbds_mitigation]);
 }
 
+static ssize_t retbleed_show_state(char *buf)
+{
+       return sprintf(buf, "Vulnerable\n");
+}
+
 static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
                               char *buf, unsigned int bug)
 {
@@ -2032,6 +2037,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
        case X86_BUG_MMIO_STALE_DATA:
                return mmio_stale_data_show_state(buf);
 
+       case X86_BUG_RETBLEED:
+               return retbleed_show_state(buf);
+
        default:
                break;
        }
@@ -2088,4 +2096,9 @@ ssize_t cpu_show_mmio_stale_data(struct device *dev, struct device_attribute *at
 {
        return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_STALE_DATA);
 }
+
+ssize_t cpu_show_retbleed(struct device *dev, struct device_attribute *attr, char *buf)
+{
+       return cpu_show_common(dev, attr, buf, X86_BUG_RETBLEED);
+}
 #endif

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index bd390c5..d5488cf 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1095,16 +1095,27 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
        {}
 };
 
+#define VULNBL(vendor, family, model, blacklist)       \
+       X86_MATCH_VENDOR_FAM_MODEL(vendor, family, model, blacklist)
+
 #define VULNBL_INTEL_STEPPINGS(model, steppings, issues)                  \
        X86_MATCH_VENDOR_FAM_MODEL_STEPPINGS_FEATURE(INTEL, 6,             \
                                            INTEL_FAM6_##model, steppings, \
                                            X86_FEATURE_ANY, issues)
 
+#define VULNBL_AMD(family, blacklist)          \
+       VULNBL(AMD, family, X86_MODEL_ANY, blacklist)
+
+#define VULNBL_HYGON(family, blacklist)                \
+       VULNBL(HYGON, family, X86_MODEL_ANY, blacklist)
+
 #define SRBDS          BIT(0)
 /* CPU is affected by X86_BUG_MMIO_STALE_DATA */
 #define MMIO           BIT(1)
 /* CPU is affected by Shared Buffers Data Sampling (SBDS), a variant of X86_BUG_MMIO_STALE_DATA */
 #define MMIO_SBDS      BIT(2)
+/* CPU is affected by RETbleed, speculating where you would not expect it */
+#define RETBLEED       BIT(3)
 
 static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
        VULNBL_INTEL_STEPPINGS(IVYBRIDGE,       X86_STEPPING_ANY,               SRBDS),
@@ -1137,6 +1148,11 @@ static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
        VULNBL_INTEL_STEPPINGS(ATOM_TREMONT,    X86_STEPPINGS(0x1, 0x1),        MMIO | MMIO_SBDS),
        VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_D,  X86_STEPPING_ANY,               MMIO),
        VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L,  X86_STEPPINGS(0x0, 0x0),        MMIO | MMIO_SBDS),
+
+       VULNBL_AMD(0x15, RETBLEED),
+       VULNBL_AMD(0x16, RETBLEED),
+       VULNBL_AMD(0x17, RETBLEED),
+       VULNBL_HYGON(0x18, RETBLEED),
        {}
 };
 
@@ -1238,6 +1254,9 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
            !arch_cap_mmio_immune(ia32_cap))
                setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA);
 
+       if (cpu_matches(cpu_vuln_blacklist, RETBLEED))
+               setup_force_cpu_bug(X86_BUG_RETBLEED);
+
        if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN))
                return;
 

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index fddd08e..55405eb 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -570,6 +570,12 @@ ssize_t __weak cpu_show_mmio_stale_data(struct device *dev,
        return sysfs_emit(buf, "Not affected\n");
 }
 
+ssize_t __weak cpu_show_retbleed(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+       return sysfs_emit(buf, "Not affected\n");
+}
+
 static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
 static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
 static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
@@ -580,6 +586,7 @@ static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL);
 static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL);
 static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL);
 static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, NULL);
+static DEVICE_ATTR(retbleed, 0444, cpu_show_retbleed, NULL);
 
 static struct attribute *cpu_root_vulnerabilities_attrs[] = {
        &dev_attr_meltdown.attr,
@@ -592,6 +599,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = {
        &dev_attr_itlb_multihit.attr,
        &dev_attr_srbds.attr,
        &dev_attr_mmio_stale_data.attr,
+       &dev_attr_retbleed.attr,
        NULL
 };
 

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index eb3394f..6102a21 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -68,6 +68,8 @@ extern ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr,
 extern ssize_t cpu_show_mmio_stale_data(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf);
+extern ssize_t cpu_show_retbleed(struct device *dev,
+                                struct device_attribute *attr, char *buf);
 
 extern __printf(4, 5)
 struct device *cpu_device_create(struct device *parent, void *drvdata,