[PATCH 2b/7] x86/bugs: Rename various 'ia32_cap' variables to 'x86_arch_cap_msr'

[Ingo Molnar <mingo@kernel.org>]

* Josh Poimboeuf <jpoimboe@kernel.org> wrote:

> There's no need to keep reading MSR_IA32_ARCH_CAPABILITIES over and
> over.  It's even read in the BHI sysfs function which is a big no-no.
> Just read it once and cache it.
> 
> Fixes: ec9404e40e8f ("x86/bhi: Add BHI mitigation knob")
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
>  arch/x86/kernel/cpu/bugs.c | 22 +++++++---------------
>  1 file changed, 7 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
> index 295463707e68..27d6d64eeec3 100644
> --- a/arch/x86/kernel/cpu/bugs.c
> +++ b/arch/x86/kernel/cpu/bugs.c
> @@ -61,6 +61,8 @@ EXPORT_PER_CPU_SYMBOL_GPL(x86_spec_ctrl_current);
>  u64 x86_pred_cmd __ro_after_init = PRED_CMD_IBPB;
>  EXPORT_SYMBOL_GPL(x86_pred_cmd);
>  
> +static u64 __ro_after_init ia32_cap;

So the 'ia32' there is a misnomer - which already exists in a number of 
other places but now becomes annoyingly commonly used.

So I did the patch below on top to clean this up and rename it to 
x86_arch_cap_msr.

Thanks,

	Ingo

==================>
From: Ingo Molnar <mingo@kernel.org>
Date: Thu, 11 Apr 2024 09:25:36 +0200
Subject: [PATCH] x86/bugs: Rename various 'ia32_cap' variables to 'x86_arch_cap_msr'

So we are using the 'ia32_cap' value in a number of places,
which got its name from MSR_IA32_ARCH_CAPABILITIES MSR register.

But there's very little 'IA32' about it - this isn't 32-bit only
code, nor does it originate from there, it's just a historic
quirk that many Intel MSR names are prefixed with IA32_.

This is already clear from the helper method around the MSR:
x86_read_arch_cap_msr(), which doesn't have the IA32 prefix.

So rename 'ia32_cap' to 'x86_arch_cap_msr' to be consistent with
its role and with the naming of the helper function.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nikolay Borisov <nik.borisov@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/9592a18a814368e75f8f4b9d74d3883aa4fd1eaf.1712813475.git.jpoimboe@kernel.org
---
 arch/x86/kernel/apic/apic.c  |  6 +++---
 arch/x86/kernel/cpu/bugs.c   | 30 +++++++++++++--------------
 arch/x86/kernel/cpu/common.c | 48 ++++++++++++++++++++++----------------------
 3 files changed, 42 insertions(+), 42 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index a42d8a6f7149..c342c4aa9c68 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1687,11 +1687,11 @@ static int x2apic_state;
 
 static bool x2apic_hw_locked(void)
 {
-	u64 ia32_cap;
+	u64 x86_arch_cap_msr;
 	u64 msr;
 
-	ia32_cap = x86_read_arch_cap_msr();
-	if (ia32_cap & ARCH_CAP_XAPIC_DISABLE) {
+	x86_arch_cap_msr = x86_read_arch_cap_msr();
+	if (x86_arch_cap_msr & ARCH_CAP_XAPIC_DISABLE) {
 		rdmsrl(MSR_IA32_XAPIC_DISABLE_STATUS, msr);
 		return (msr & LEGACY_XAPIC_DISABLED);
 	}
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 61614d69d71b..eb9972bf154a 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -61,7 +61,7 @@ EXPORT_PER_CPU_SYMBOL_GPL(x86_spec_ctrl_current);
 u64 x86_pred_cmd __ro_after_init = PRED_CMD_IBPB;
 EXPORT_SYMBOL_GPL(x86_pred_cmd);
 
-static u64 __ro_after_init ia32_cap;
+static u64 __ro_after_init x86_arch_cap_msr;
 
 static DEFINE_MUTEX(spec_ctrl_mutex);
 
@@ -146,7 +146,7 @@ void __init cpu_select_mitigations(void)
 		x86_spec_ctrl_base &= ~SPEC_CTRL_MITIGATIONS_MASK;
 	}
 
-	ia32_cap = x86_read_arch_cap_msr();
+	x86_arch_cap_msr = x86_read_arch_cap_msr();
 
 	/* Select the proper CPU mitigations before patching alternatives: */
 	spectre_v1_select_mitigation();
@@ -343,8 +343,8 @@ static void __init taa_select_mitigation(void)
 	 * On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode
 	 * update is required.
 	 */
-	if ( (ia32_cap & ARCH_CAP_MDS_NO) &&
-	    !(ia32_cap & ARCH_CAP_TSX_CTRL_MSR))
+	if ( (x86_arch_cap_msr & ARCH_CAP_MDS_NO) &&
+	    !(x86_arch_cap_msr & ARCH_CAP_TSX_CTRL_MSR))
 		taa_mitigation = TAA_MITIGATION_UCODE_NEEDED;
 
 	/*
@@ -434,7 +434,7 @@ static void __init mmio_select_mitigation(void)
 	 * be propagated to uncore buffers, clearing the Fill buffers on idle
 	 * is required irrespective of SMT state.
 	 */
-	if (!(ia32_cap & ARCH_CAP_FBSDP_NO))
+	if (!(x86_arch_cap_msr & ARCH_CAP_FBSDP_NO))
 		static_branch_enable(&mds_idle_clear);
 
 	/*
@@ -444,10 +444,10 @@ static void __init mmio_select_mitigation(void)
 	 * FB_CLEAR or by the presence of both MD_CLEAR and L1D_FLUSH on MDS
 	 * affected systems.
 	 */
-	if ((ia32_cap & ARCH_CAP_FB_CLEAR) ||
+	if ((x86_arch_cap_msr & ARCH_CAP_FB_CLEAR) ||
 	    (boot_cpu_has(X86_FEATURE_MD_CLEAR) &&
 	     boot_cpu_has(X86_FEATURE_FLUSH_L1D) &&
-	     !(ia32_cap & ARCH_CAP_MDS_NO)))
+	     !(x86_arch_cap_msr & ARCH_CAP_MDS_NO)))
 		mmio_mitigation = MMIO_MITIGATION_VERW;
 	else
 		mmio_mitigation = MMIO_MITIGATION_UCODE_NEEDED;
@@ -505,7 +505,7 @@ static void __init rfds_select_mitigation(void)
 	if (rfds_mitigation == RFDS_MITIGATION_OFF)
 		return;
 
-	if (ia32_cap & ARCH_CAP_RFDS_CLEAR)
+	if (x86_arch_cap_msr & ARCH_CAP_RFDS_CLEAR)
 		setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF);
 	else
 		rfds_mitigation = RFDS_MITIGATION_UCODE_NEEDED;
@@ -664,7 +664,7 @@ static void __init srbds_select_mitigation(void)
 	 * are only exposed to SRBDS when TSX is enabled or when CPU is affected
 	 * by Processor MMIO Stale Data vulnerability.
 	 */
-	if ((ia32_cap & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) &&
+	if ((x86_arch_cap_msr & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) &&
 	    !boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
 		srbds_mitigation = SRBDS_MITIGATION_TSX_OFF;
 	else if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
@@ -807,7 +807,7 @@ static void __init gds_select_mitigation(void)
 	/* Will verify below that mitigation _can_ be disabled */
 
 	/* No microcode */
-	if (!(ia32_cap & ARCH_CAP_GDS_CTRL)) {
+	if (!(x86_arch_cap_msr & ARCH_CAP_GDS_CTRL)) {
 		if (gds_mitigation == GDS_MITIGATION_FORCE) {
 			/*
 			 * This only needs to be done on the boot CPU so do it
@@ -1541,14 +1541,14 @@ static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void)
 /* Disable in-kernel use of non-RSB RET predictors */
 static void __init spec_ctrl_disable_kernel_rrsba(void)
 {
-	u64 ia32_cap;
+	u64 x86_arch_cap_msr;
 
 	if (!boot_cpu_has(X86_FEATURE_RRSBA_CTRL))
 		return;
 
-	ia32_cap = x86_read_arch_cap_msr();
+	x86_arch_cap_msr = x86_read_arch_cap_msr();
 
-	if (ia32_cap & ARCH_CAP_RRSBA) {
+	if (x86_arch_cap_msr & ARCH_CAP_RRSBA) {
 		x86_spec_ctrl_base |= SPEC_CTRL_RRSBA_DIS_S;
 		update_spec_ctrl(x86_spec_ctrl_base);
 	}
@@ -1916,7 +1916,7 @@ static void update_mds_branch_idle(void)
 	if (sched_smt_active()) {
 		static_branch_enable(&mds_idle_clear);
 	} else if (mmio_mitigation == MMIO_MITIGATION_OFF ||
-		   (ia32_cap & ARCH_CAP_FBSDP_NO)) {
+		   (x86_arch_cap_msr & ARCH_CAP_FBSDP_NO)) {
 		static_branch_disable(&mds_idle_clear);
 	}
 }
@@ -2810,7 +2810,7 @@ static const char *spectre_bhi_state(void)
 	else if  (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP))
 		return "; BHI: SW loop, KVM: SW loop";
 	else if (boot_cpu_has(X86_FEATURE_RETPOLINE) &&
-		 !(ia32_cap & ARCH_CAP_RRSBA))
+		 !(x86_arch_cap_msr & ARCH_CAP_RRSBA))
 		return "; BHI: Retpoline";
 	else if  (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT))
 		return "; BHI: Syscall hardening, KVM: SW loop";
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 754d91857d63..605c26c009c8 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1284,25 +1284,25 @@ static bool __init cpu_matches(const struct x86_cpu_id *table, unsigned long whi
 
 u64 x86_read_arch_cap_msr(void)
 {
-	u64 ia32_cap = 0;
+	u64 x86_arch_cap_msr = 0;
 
 	if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))
-		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);
+		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, x86_arch_cap_msr);
 
-	return ia32_cap;
+	return x86_arch_cap_msr;
 }
 
-static bool arch_cap_mmio_immune(u64 ia32_cap)
+static bool arch_cap_mmio_immune(u64 x86_arch_cap_msr)
 {
-	return (ia32_cap & ARCH_CAP_FBSDP_NO &&
-		ia32_cap & ARCH_CAP_PSDP_NO &&
-		ia32_cap & ARCH_CAP_SBDR_SSDP_NO);
+	return (x86_arch_cap_msr & ARCH_CAP_FBSDP_NO &&
+		x86_arch_cap_msr & ARCH_CAP_PSDP_NO &&
+		x86_arch_cap_msr & ARCH_CAP_SBDR_SSDP_NO);
 }
 
-static bool __init vulnerable_to_rfds(u64 ia32_cap)
+static bool __init vulnerable_to_rfds(u64 x86_arch_cap_msr)
 {
 	/* The "immunity" bit trumps everything else: */
-	if (ia32_cap & ARCH_CAP_RFDS_NO)
+	if (x86_arch_cap_msr & ARCH_CAP_RFDS_NO)
 		return false;
 
 	/*
@@ -1310,7 +1310,7 @@ static bool __init vulnerable_to_rfds(u64 ia32_cap)
 	 * indicate that mitigation is needed because guest is running on a
 	 * vulnerable hardware or may migrate to such hardware:
 	 */
-	if (ia32_cap & ARCH_CAP_RFDS_CLEAR)
+	if (x86_arch_cap_msr & ARCH_CAP_RFDS_CLEAR)
 		return true;
 
 	/* Only consult the blacklist when there is no enumeration: */
@@ -1319,11 +1319,11 @@ static bool __init vulnerable_to_rfds(u64 ia32_cap)
 
 static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 {
-	u64 ia32_cap = x86_read_arch_cap_msr();
+	u64 x86_arch_cap_msr = x86_read_arch_cap_msr();
 
 	/* Set ITLB_MULTIHIT bug if cpu is not in the whitelist and not mitigated */
 	if (!cpu_matches(cpu_vuln_whitelist, NO_ITLB_MULTIHIT) &&
-	    !(ia32_cap & ARCH_CAP_PSCHANGE_MC_NO))
+	    !(x86_arch_cap_msr & ARCH_CAP_PSCHANGE_MC_NO))
 		setup_force_cpu_bug(X86_BUG_ITLB_MULTIHIT);
 
 	if (cpu_matches(cpu_vuln_whitelist, NO_SPECULATION))
@@ -1335,7 +1335,7 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 		setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
 
 	if (!cpu_matches(cpu_vuln_whitelist, NO_SSB) &&
-	    !(ia32_cap & ARCH_CAP_SSB_NO) &&
+	    !(x86_arch_cap_msr & ARCH_CAP_SSB_NO) &&
 	   !cpu_has(c, X86_FEATURE_AMD_SSB_NO))
 		setup_force_cpu_bug(X86_BUG_SPEC_STORE_BYPASS);
 
@@ -1346,17 +1346,17 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 	 * Don't use AutoIBRS when SNP is enabled because it degrades host
 	 * userspace indirect branch performance.
 	 */
-	if ((ia32_cap & ARCH_CAP_IBRS_ALL) ||
+	if ((x86_arch_cap_msr & ARCH_CAP_IBRS_ALL) ||
 	    (cpu_has(c, X86_FEATURE_AUTOIBRS) &&
 	     !cpu_feature_enabled(X86_FEATURE_SEV_SNP))) {
 		setup_force_cpu_cap(X86_FEATURE_IBRS_ENHANCED);
 		if (!cpu_matches(cpu_vuln_whitelist, NO_EIBRS_PBRSB) &&
-		    !(ia32_cap & ARCH_CAP_PBRSB_NO))
+		    !(x86_arch_cap_msr & ARCH_CAP_PBRSB_NO))
 			setup_force_cpu_bug(X86_BUG_EIBRS_PBRSB);
 	}
 
 	if (!cpu_matches(cpu_vuln_whitelist, NO_MDS) &&
-	    !(ia32_cap & ARCH_CAP_MDS_NO)) {
+	    !(x86_arch_cap_msr & ARCH_CAP_MDS_NO)) {
 		setup_force_cpu_bug(X86_BUG_MDS);
 		if (cpu_matches(cpu_vuln_whitelist, MSBDS_ONLY))
 			setup_force_cpu_bug(X86_BUG_MSBDS_ONLY);
@@ -1375,9 +1375,9 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 	 * TSX_CTRL check alone is not sufficient for cases when the microcode
 	 * update is not present or running as guest that don't get TSX_CTRL.
 	 */
-	if (!(ia32_cap & ARCH_CAP_TAA_NO) &&
+	if (!(x86_arch_cap_msr & ARCH_CAP_TAA_NO) &&
 	    (cpu_has(c, X86_FEATURE_RTM) ||
-	     (ia32_cap & ARCH_CAP_TSX_CTRL_MSR)))
+	     (x86_arch_cap_msr & ARCH_CAP_TSX_CTRL_MSR)))
 		setup_force_cpu_bug(X86_BUG_TAA);
 
 	/*
@@ -1403,7 +1403,7 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 	 * Set X86_BUG_MMIO_UNKNOWN for CPUs that are neither in the blacklist,
 	 * nor in the whitelist and also don't enumerate MSR ARCH_CAP MMIO bits.
 	 */
-	if (!arch_cap_mmio_immune(ia32_cap)) {
+	if (!arch_cap_mmio_immune(x86_arch_cap_msr)) {
 		if (cpu_matches(cpu_vuln_blacklist, MMIO))
 			setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA);
 		else if (!cpu_matches(cpu_vuln_whitelist, NO_MMIO))
@@ -1411,7 +1411,7 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 	}
 
 	if (!cpu_has(c, X86_FEATURE_BTC_NO)) {
-		if (cpu_matches(cpu_vuln_blacklist, RETBLEED) || (ia32_cap & ARCH_CAP_RSBA))
+		if (cpu_matches(cpu_vuln_blacklist, RETBLEED) || (x86_arch_cap_msr & ARCH_CAP_RSBA))
 			setup_force_cpu_bug(X86_BUG_RETBLEED);
 	}
 
@@ -1429,15 +1429,15 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 	 * disabling AVX2. The only way to do this in HW is to clear XCR0[2],
 	 * which means that AVX will be disabled.
 	 */
-	if (cpu_matches(cpu_vuln_blacklist, GDS) && !(ia32_cap & ARCH_CAP_GDS_NO) &&
+	if (cpu_matches(cpu_vuln_blacklist, GDS) && !(x86_arch_cap_msr & ARCH_CAP_GDS_NO) &&
 	    boot_cpu_has(X86_FEATURE_AVX))
 		setup_force_cpu_bug(X86_BUG_GDS);
 
-	if (vulnerable_to_rfds(ia32_cap))
+	if (vulnerable_to_rfds(x86_arch_cap_msr))
 		setup_force_cpu_bug(X86_BUG_RFDS);
 
 	/* When virtualized, eIBRS could be hidden, assume vulnerable */
-	if (!(ia32_cap & ARCH_CAP_BHI_NO) &&
+	if (!(x86_arch_cap_msr & ARCH_CAP_BHI_NO) &&
 	    !cpu_matches(cpu_vuln_whitelist, NO_BHI) &&
 	    (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED) ||
 	     boot_cpu_has(X86_FEATURE_HYPERVISOR)))
@@ -1447,7 +1447,7 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 		return;
 
 	/* Rogue Data Cache Load? No! */
-	if (ia32_cap & ARCH_CAP_RDCL_NO)
+	if (x86_arch_cap_msr & ARCH_CAP_RDCL_NO)
 		return;
 
 	setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);