From: Adam Dunlap <acdunlap@google.com>
Date: Tue, 12 Sep 2023 00:27:03 +0000 (-0700)
Subject: x86/sev-es: Set x86_virt_bits to the correct value straight away, instead of a two... 
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=fbf6449f84bf5e4ad09f2c09ee70ed7d629b5ff6;p=linux.git

x86/sev-es: Set x86_virt_bits to the correct value straight away, instead of a two-phase approach

Instead of setting x86_virt_bits to a possibly-correct value and then
correcting it later, do all the necessary checks before setting it.

At this point, the #VC handler references boot_cpu_data.x86_virt_bits,
and in the previous version, it would be triggered by the CPUIDs between
the point at which it is set to 48 and when it is set to the correct
value.

Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Adam Dunlap <acdunlap@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Jacob Xu <jacobhxu@google.com>
Link: https://lore.kernel.org/r/20230912002703.3924521-3-acdunlap@google.com
---

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 382d4e6b848d2..8d7063e4f63c9 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1114,17 +1114,32 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
 void get_cpu_address_sizes(struct cpuinfo_x86 *c)
 {
 	u32 eax, ebx, ecx, edx;
+	bool vp_bits_from_cpuid = true;
 
-	if (c->extended_cpuid_level >= 0x80000008) {
+	if (!cpu_has(c, X86_FEATURE_CPUID) ||
+	    (c->extended_cpuid_level < 0x80000008))
+		vp_bits_from_cpuid = false;
+
+	if (vp_bits_from_cpuid) {
 		cpuid(0x80000008, &eax, &ebx, &ecx, &edx);
 
 		c->x86_virt_bits = (eax >> 8) & 0xff;
 		c->x86_phys_bits = eax & 0xff;
+	} else {
+		if (IS_ENABLED(CONFIG_X86_64)) {
+			c->x86_clflush_size = 64;
+			c->x86_phys_bits = 36;
+			c->x86_virt_bits = 48;
+		} else {
+			c->x86_clflush_size = 32;
+			c->x86_virt_bits = 32;
+			c->x86_phys_bits = 32;
+
+			if (cpu_has(c, X86_FEATURE_PAE) ||
+			    cpu_has(c, X86_FEATURE_PSE36))
+				c->x86_phys_bits = 36;
+		}
 	}
-#ifdef CONFIG_X86_32
-	else if (cpu_has(c, X86_FEATURE_PAE) || cpu_has(c, X86_FEATURE_PSE36))
-		c->x86_phys_bits = 36;
-#endif
 	c->x86_cache_bits = c->x86_phys_bits;
 }
 
@@ -1579,15 +1594,6 @@ static void __init cpu_parse_early_param(void)
  */
 static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 {
-#ifdef CONFIG_X86_64
-	c->x86_clflush_size = 64;
-	c->x86_phys_bits = 36;
-	c->x86_virt_bits = 48;
-#else
-	c->x86_clflush_size = 32;
-	c->x86_phys_bits = 32;
-	c->x86_virt_bits = 32;
-#endif
 	c->x86_cache_alignment = c->x86_clflush_size;
 
 	memset(&c->x86_capability, 0, sizeof(c->x86_capability));
@@ -1601,7 +1607,6 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 		cpu_detect(c);
 		get_cpu_vendor(c);
 		get_cpu_cap(c);
-		get_cpu_address_sizes(c);
 		setup_force_cpu_cap(X86_FEATURE_CPUID);
 		cpu_parse_early_param();
 
@@ -1617,6 +1622,8 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 		setup_clear_cpu_cap(X86_FEATURE_CPUID);
 	}
 
+	get_cpu_address_sizes(c);
+
 	setup_force_cpu_cap(X86_FEATURE_ALWAYS);
 
 	cpu_set_bug_bits(c);