[RFC][PATCH 25/34] x86/cpu: Move cache bits to global config

[Dave Hansen]

From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

x86_cache_bits is established and stored per-cpu despite being system-wide.
Move it from 'struct cpuinfo_x86' to 'x86_config' and give it a helper.

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
---

 b/arch/x86/include/asm/processor.h |   10 +++++++---
 b/arch/x86/kernel/cpu/common.c     |    8 ++++----
 b/arch/x86/kvm/mmu/spte.c          |    6 +++---
 3 files changed, 14 insertions(+), 10 deletions(-)

diff -puN arch/x86/include/asm/processor.h~config-cache_bits arch/x86/include/asm/processor.h
--- a/arch/x86/include/asm/processor.h~config-cache_bits	2024-02-22 10:09:00.768936544 -0800
+++ b/arch/x86/include/asm/processor.h	2024-02-22 10:09:00.772936701 -0800
@@ -154,8 +154,6 @@ struct cpuinfo_x86 {
 	/*  Is SMT active on this core? */
 	bool			smt_active;
 	u32			microcode;
-	/* Address space bits used by the cache internally */
-	u8			x86_cache_bits;
 	unsigned		initialized : 1;
 } __randomize_layout;
 
@@ -195,6 +193,7 @@ struct x86_sys_config {
 	/* Address bits supported by all processors */
 	u8	phys_bits;
 	u8	virt_bits;
+	u8	cache_bits;
 	u16	clflush_size;
 	int	cache_alignment; /* in bytes */
 };
@@ -241,7 +240,7 @@ extern void cpu_detect(struct cpuinfo_x8
 
 static inline unsigned long long l1tf_pfn_limit(void)
 {
-	return BIT_ULL(boot_cpu_data.x86_cache_bits - 1 - PAGE_SHIFT);
+	return BIT_ULL(x86_config.cache_bits - 1 - PAGE_SHIFT);
 }
 
 extern void early_cpu_init(void);
@@ -816,6 +815,11 @@ static inline u8 x86_virt_bits(void)
 	return x86_config.virt_bits;
 }
 
+static inline u8 x86_cache_bits(void)
+{
+	return x86_config.cache_bits;
+}
+
 static inline u8 x86_clflush_size(void)
 {
 	return x86_config.clflush_size;
diff -puN arch/x86/kernel/cpu/common.c~config-cache_bits arch/x86/kernel/cpu/common.c
--- a/arch/x86/kernel/cpu/common.c~config-cache_bits	2024-02-22 10:09:00.768936544 -0800
+++ b/arch/x86/kernel/cpu/common.c	2024-02-22 10:09:00.772936701 -0800
@@ -1138,15 +1138,15 @@ void get_cpu_address_sizes(struct cpuinf
 	}
 	x86_config.clflush_size = detect_clflush_size(c);
 
-	c->x86_cache_bits = x86_config.phys_bits;
-	if (c->x86_cache_bits < bsp_addr_config.min_cache_bits)
-		c->x86_cache_bits = bsp_addr_config.min_cache_bits;
+	x86_config.cache_bits = x86_config.phys_bits;
+	if (x86_config.cache_bits < bsp_addr_config.min_cache_bits)
+		x86_config.cache_bits = bsp_addr_config.min_cache_bits;
 
 	x86_config.cache_alignment = x86_clflush_size();
 	if (bsp_addr_config.cache_align_mult)
 		x86_config.cache_alignment *= bsp_addr_config.cache_align_mult;
 
-	/* Do this last to avoid affecting ->x86_cache_bits. */
+	/* Do this last to avoid affecting '.cache_bits'. */
 	x86_config.phys_bits -= bsp_addr_config.phys_addr_reduction_bits;
 }
 
diff -puN arch/x86/kvm/mmu/spte.c~config-cache_bits arch/x86/kvm/mmu/spte.c
--- a/arch/x86/kvm/mmu/spte.c~config-cache_bits	2024-02-22 10:09:00.772936701 -0800
+++ b/arch/x86/kvm/mmu/spte.c	2024-02-22 10:09:00.772936701 -0800
@@ -470,12 +470,12 @@ void kvm_mmu_reset_all_pte_masks(void)
 	shadow_nonpresent_or_rsvd_mask = 0;
 	low_phys_bits = x86_phys_bits();
 	if (boot_cpu_has_bug(X86_BUG_L1TF) &&
-	    !WARN_ON_ONCE(boot_cpu_data.x86_cache_bits >=
+	    !WARN_ON_ONCE(x86_cache_bits() >=
 			  52 - SHADOW_NONPRESENT_OR_RSVD_MASK_LEN)) {
-		low_phys_bits = boot_cpu_data.x86_cache_bits
+		low_phys_bits = x86_cache_bits()
 			- SHADOW_NONPRESENT_OR_RSVD_MASK_LEN;
 		shadow_nonpresent_or_rsvd_mask =
-			rsvd_bits(low_phys_bits, boot_cpu_data.x86_cache_bits - 1);
+			rsvd_bits(low_phys_bits, x86_cache_bits() - 1);
 	}
 
 	shadow_nonpresent_or_rsvd_lower_gfn_mask =
_