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x86/cpu/amd: Enumerate BTC_NO
commit 26aae8ccbc
upstream.
BTC_NO indicates that hardware is not susceptible to Branch Type Confusion.
Zen3 CPUs don't suffer BTC.
Hypervisors are expected to synthesise BTC_NO when it is appropriate
given the migration pool, to prevent kernels using heuristics.
[ bp: Massage. ]
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
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>
This commit is contained in:
parent
2edfa537f3
commit
d6a8a470dc
3 changed files with 20 additions and 8 deletions
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@ -304,6 +304,7 @@
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#define X86_FEATURE_AMD_SSBD (13*32+24) /* "" Speculative Store Bypass Disable */
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#define X86_FEATURE_VIRT_SSBD (13*32+25) /* Virtualized Speculative Store Bypass Disable */
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#define X86_FEATURE_AMD_SSB_NO (13*32+26) /* "" Speculative Store Bypass is fixed in hardware. */
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#define X86_FEATURE_BTC_NO (13*32+29) /* "" Not vulnerable to Branch Type Confusion */
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/* Thermal and Power Management Leaf, CPUID level 0x00000006 (EAX), word 14 */
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#define X86_FEATURE_DTHERM (14*32+ 0) /* Digital Thermal Sensor */
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@ -894,12 +894,21 @@ static void init_amd_zn(struct cpuinfo_x86 *c)
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node_reclaim_distance = 32;
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#endif
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/*
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* Fix erratum 1076: CPB feature bit not being set in CPUID.
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* Always set it, except when running under a hypervisor.
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*/
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if (!cpu_has(c, X86_FEATURE_HYPERVISOR) && !cpu_has(c, X86_FEATURE_CPB))
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set_cpu_cap(c, X86_FEATURE_CPB);
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/* Fix up CPUID bits, but only if not virtualised. */
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if (!cpu_has(c, X86_FEATURE_HYPERVISOR)) {
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/* Erratum 1076: CPB feature bit not being set in CPUID. */
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if (!cpu_has(c, X86_FEATURE_CPB))
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set_cpu_cap(c, X86_FEATURE_CPB);
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/*
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* Zen3 (Fam19 model < 0x10) parts are not susceptible to
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* Branch Type Confusion, but predate the allocation of the
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* BTC_NO bit.
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*/
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if (c->x86 == 0x19 && !cpu_has(c, X86_FEATURE_BTC_NO))
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set_cpu_cap(c, X86_FEATURE_BTC_NO);
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}
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}
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static void init_amd(struct cpuinfo_x86 *c)
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@ -1259,8 +1259,10 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
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setup_force_cpu_bug(X86_BUG_MMIO_UNKNOWN);
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}
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if ((cpu_matches(cpu_vuln_blacklist, RETBLEED) || (ia32_cap & ARCH_CAP_RSBA)))
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setup_force_cpu_bug(X86_BUG_RETBLEED);
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if (!cpu_has(c, X86_FEATURE_BTC_NO)) {
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if (cpu_matches(cpu_vuln_blacklist, RETBLEED) || (ia32_cap & ARCH_CAP_RSBA))
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setup_force_cpu_bug(X86_BUG_RETBLEED);
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}
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if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN))
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return;
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