From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
To: stable@vger.kernel.org
Cc: x86@kernel.org, kvm@vger.kernel.org, bp@alien8.de,
pbonzini@redhat.com, peterz@infradead.org, jpoimboe@kernel.org
Subject: [PATCH 5.4 32/37] x86/cpu/amd: Enumerate BTC_NO
Date: Mon, 3 Oct 2022 10:10:33 -0300 [thread overview]
Message-ID: <20221003131038.12645-33-cascardo@canonical.com> (raw)
In-Reply-To: <20221003131038.12645-1-cascardo@canonical.com>
From: Andrew Cooper <andrew.cooper3@citrix.com>
commit 26aae8ccbc1972233afd08fb3f368947c0314265 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>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/kernel/cpu/amd.c | 21 +++++++++++++++------
arch/x86/kernel/cpu/common.c | 6 ++++--
3 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 611efccdc742..d6fc05367439 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -304,6 +304,7 @@
#define X86_FEATURE_AMD_SSBD (13*32+24) /* "" Speculative Store Bypass Disable */
#define X86_FEATURE_VIRT_SSBD (13*32+25) /* Virtualized Speculative Store Bypass Disable */
#define X86_FEATURE_AMD_SSB_NO (13*32+26) /* "" Speculative Store Bypass is fixed in hardware. */
+#define X86_FEATURE_BTC_NO (13*32+29) /* "" Not vulnerable to Branch Type Confusion */
/* Thermal and Power Management Leaf, CPUID level 0x00000006 (EAX), word 14 */
#define X86_FEATURE_DTHERM (14*32+ 0) /* Digital Thermal Sensor */
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 88cef978380b..5571b28d35b6 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -894,12 +894,21 @@ static void init_amd_zn(struct cpuinfo_x86 *c)
node_reclaim_distance = 32;
#endif
- /*
- * Fix erratum 1076: CPB feature bit not being set in CPUID.
- * Always set it, except when running under a hypervisor.
- */
- if (!cpu_has(c, X86_FEATURE_HYPERVISOR) && !cpu_has(c, X86_FEATURE_CPB))
- set_cpu_cap(c, X86_FEATURE_CPB);
+ /* Fix up CPUID bits, but only if not virtualised. */
+ if (!cpu_has(c, X86_FEATURE_HYPERVISOR)) {
+
+ /* Erratum 1076: CPB feature bit not being set in CPUID. */
+ if (!cpu_has(c, X86_FEATURE_CPB))
+ set_cpu_cap(c, X86_FEATURE_CPB);
+
+ /*
+ * Zen3 (Fam19 model < 0x10) parts are not susceptible to
+ * Branch Type Confusion, but predate the allocation of the
+ * BTC_NO bit.
+ */
+ if (c->x86 == 0x19 && !cpu_has(c, X86_FEATURE_BTC_NO))
+ set_cpu_cap(c, X86_FEATURE_BTC_NO);
+ }
}
static void init_amd(struct cpuinfo_x86 *c)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 4035581f61e0..0002dc62214d 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1259,8 +1259,10 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
setup_force_cpu_bug(X86_BUG_MMIO_UNKNOWN);
}
- if ((cpu_matches(cpu_vuln_blacklist, RETBLEED) || (ia32_cap & ARCH_CAP_RSBA)))
- setup_force_cpu_bug(X86_BUG_RETBLEED);
+ if (!cpu_has(c, X86_FEATURE_BTC_NO)) {
+ if (cpu_matches(cpu_vuln_blacklist, RETBLEED) || (ia32_cap & ARCH_CAP_RSBA))
+ setup_force_cpu_bug(X86_BUG_RETBLEED);
+ }
if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN))
return;
--
2.34.1
next prev parent reply other threads:[~2022-10-03 13:13 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-03 13:10 [PATCH 5.4 00/37] IBRS support // Retbleed mitigations Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 01/37] Revert "x86/speculation: Add RSB VM Exit protections" Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 02/37] Revert "x86/cpu: Add a steppings field to struct x86_cpu_id" Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 03/37] x86/devicetable: Move x86 specific macro out of generic code Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 04/37] x86/cpu: Add consistent CPU match macros Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 05/37] x86/cpu: Add a steppings field to struct x86_cpu_id Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 06/37] x86/kvm/vmx: Make noinstr clean Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 07/37] x86/cpufeatures: Move RETPOLINE flags to word 11 Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 08/37] x86/bugs: Report AMD retbleed vulnerability Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 09/37] x86/bugs: Add AMD retbleed= boot parameter Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 10/37] x86/bugs: Keep a per-CPU IA32_SPEC_CTRL value Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 11/37] x86/entry: Remove skip_r11rcx Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 12/37] x86/entry: Add kernel IBRS implementation Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 13/37] x86/bugs: Optimize SPEC_CTRL MSR writes Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 14/37] x86/speculation: Add spectre_v2=ibrs option to support Kernel IBRS Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 15/37] x86/bugs: Split spectre_v2_select_mitigation() and spectre_v2_user_select_mitigation() Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 16/37] x86/bugs: Report Intel retbleed vulnerability Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 17/37] intel_idle: Disable IBRS during long idle Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 18/37] x86/speculation: Change FILL_RETURN_BUFFER to work with objtool Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 19/37] x86/speculation: Fix RSB filling with CONFIG_RETPOLINE=n Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 20/37] x86/speculation: Fix firmware entry SPEC_CTRL handling Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 21/37] x86/speculation: Fix SPEC_CTRL write on SMT state change Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 22/37] x86/speculation: Use cached host SPEC_CTRL value for guest entry/exit Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 23/37] x86/speculation: Remove x86_spec_ctrl_mask Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 24/37] KVM/VMX: Use TEST %REG,%REG instead of CMP $0,%REG in vmenter.S Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 25/37] KVM/nVMX: Use __vmx_vcpu_run in nested_vmx_check_vmentry_hw Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 26/37] KVM: VMX: Flatten __vmx_vcpu_run() Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 27/37] KVM: VMX: Convert launched argument to flags Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 28/37] KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 29/37] KVM: VMX: Fix IBRS handling after vmexit Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 30/37] x86/speculation: Fill RSB on vmexit for IBRS Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 31/37] x86/common: Stamp out the stepping madness Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` Thadeu Lima de Souza Cascardo [this message]
2022-10-03 13:10 ` [PATCH 5.4 33/37] x86/bugs: Add Cannon lake to RETBleed affected CPU list Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 34/37] x86/speculation: Disable RRSBA behavior Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 35/37] x86/speculation: Use DECLARE_PER_CPU for x86_spec_ctrl_current Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 36/37] x86/bugs: Warn when "ibrs" mitigation is selected on Enhanced IBRS parts Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 37/37] x86/speculation: Add RSB VM Exit protections Thadeu Lima de Souza Cascardo
2022-10-05 10:34 ` [PATCH 5.4 00/37] IBRS support // Retbleed mitigations Greg KH
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