On Fri, Jul 29, 2022 at 04:05:29PM +0200, Borislav Petkov wrote:
On Thu, Jul 28, 2022 at 07:28:51PM -0700, Pawan Gupta wrote:
To keep things simple, can this stay in cpu/common.c?
I know, right?
The gullible maintainer should simply take your half-baked patch so that you can check off that box and then he can clean it up later.
I am sorry if it felt like that, its really not my intention.
I did also say:
"And if there is a compelling reason, I am willing to make the required changes."
I was genuinely curious about why not to use cpu/common.c for mmio.
cpu/common.c is heavily used for bugs infrastructure. It already has the affected tables, bug enumerations and helper functions for previous bugs. Maybe it needs a cleanup as a whole.
See if this works:
Thanks for this.
diff --git a/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst index 9393c50b5afc..14cd3c6ddec6 100644 --- a/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst +++ b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst @@ -230,6 +230,21 @@ The possible values in this file are: * - 'Mitigation: Clear CPU buffers' - The processor is vulnerable and the CPU buffer clearing mitigation is enabled.
* - 'Unknown: CPU is beyond its servicing period'- The processor vulnerability status is unknown because it isout of Servicing period. Mitigation is not attempted.+Definitions: +------------
+Servicing period: The process of providing functional and security +updates to Intel processors or platforms, utilizing the Intel Platform +Update (IPU) process or other similar mechanisms.
+End of Servicing Updates (ESU): ESU is the date at which Intel will no +longer provide Servicing, such as through IPU or other similar update +processes. ESU dates will typically be aligned to end of quarter. If the processor is vulnerable then the following information is appended to the above information: diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index ea34cc31b047..fe66e94d7b86 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -154,6 +154,7 @@ extern void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int bit); } while (0) #define setup_force_cpu_bug(bit) setup_force_cpu_cap(bit) +#define setup_clear_cpu_bug(bit) setup_clear_cpu_cap(bit) #if defined(__clang__) && !defined(CONFIG_CC_HAS_ASM_GOTO) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 5fe7f6c8a7a4..130cb46ecaf9 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -454,7 +454,8 @@ #define X86_BUG_TAA X86_BUG(22) /* CPU is affected by TSX Async Abort(TAA) */ #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 */ +#define X86_BUG_MMIO_UNKNOWN X86_BUG(25) /* CPU is too old and its MMIO Stale Data status is unknown */ +#define X86_BUG_MMIO_STALE_DATA X86_BUG(26) /* CPU is affected by Processor MMIO Stale Data vulnerabilities */ +#define X86_BUG_RETBLEED X86_BUG(27) /* 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 6454bc767f0f..a83d1c4265ae 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -433,7 +433,8 @@ static void __init mmio_select_mitigation(void) u64 ia32_cap; if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) ||
cpu_mitigations_off()) {
boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN) ||cpu_mitigations_off()) {
@@ -2247,6 +2248,9 @@ static ssize_t tsx_async_abort_show_state(char *buf) static ssize_t mmio_stale_data_show_state(char *buf) {
- if (boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN))
return sysfs_emit(buf, "Unknown: CPU is beyond its servicing period\n");- if (mmio_mitigation == MMIO_MITIGATION_OFF) return sysfs_emit(buf, "%s\n", mmio_strings[mmio_mitigation]);
@@ -2378,6 +2382,7 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr return srbds_show_state(buf); case X86_BUG_MMIO_STALE_DATA:
- case X86_BUG_MMIO_UNKNOWN: return mmio_stale_data_show_state(buf);
case X86_BUG_RETBLEED: @@ -2437,7 +2442,10 @@ ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char * ssize_t cpu_show_mmio_stale_data(struct device *dev, struct device_attribute *attr, char *buf) {
- return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_STALE_DATA);
- if (boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN))
return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_UNKNOWN);- else
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) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 736262a76a12..fb3e8576a3b4 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1356,9 +1356,13 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c) * but for virtualization case check for ARCH_CAP MSR bits also, VMM may * not want the guest to enumerate the bug. */
- if (cpu_matches(cpu_vuln_blacklist, MMIO) &&
!arch_cap_mmio_immune(ia32_cap))setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA);
- if (boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN)) {
This should be !boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN). Otherwise X86_BUG_MMIO_STALE_DATA will not be set on affected systems.
if (cpu_matches(cpu_vuln_blacklist, MMIO) &&!arch_cap_mmio_immune(ia32_cap)) {setup_clear_cpu_bug(X86_BUG_MMIO_UNKNOWN);
Clearing X86_BUG_MMIO_UNKNOWN wont be required then.
setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA);}- }
Does this look okay:
- if (cpu_matches(cpu_vuln_blacklist, MMIO) && - !arch_cap_mmio_immune(ia32_cap)) - setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA); + if (!boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN)) { + if (cpu_matches(cpu_vuln_blacklist, MMIO) && + !arch_cap_mmio_immune(ia32_cap)) { + setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA); + } + }
if (!cpu_has(c, X86_FEATURE_BTC_NO)) { if (cpu_matches(cpu_vuln_blacklist, RETBLEED) || (ia32_cap & ARCH_CAP_RSBA)) diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 663f6e6dd288..5b2508adc38a 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -372,6 +372,10 @@ static void early_init_intel(struct cpuinfo_x86 *c) static void bsp_init_intel(struct cpuinfo_x86 *c) { resctrl_cpu_detect(c);
- /* Set on older crap */
- if (c->x86_model < INTEL_FAM6_IVYBRIDGE)
setup_force_cpu_bug(X86_BUG_MMIO_UNKNOWN);
Thanks for suggesting this approach.