diff mbox series

[SRU,mantic:linux-gcp,lunar:linux-gcp,2/2] x86/sev-es: Only set x86_virt_bits to correct value

Message ID 20230925183922.71728-3-john.cabaj@canonical.com
State New
Headers show
Series SEV_SNP failure to init | expand

Commit Message

John Cabaj Sept. 25, 2023, 6:39 p.m. UTC 
From: Adam Dunlap <acdunlap@google.com>

BugLink: https://bugs.launchpad.net/bugs/2037316

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>
Link: https://lore.kernel.org/lkml/20230912002703.3924521-3-acdunlap@google.com/
Signed-off-by: John Cabaj <john.cabaj@canonical.com>
---
 arch/x86/kernel/cpu/common.c | 37 +++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index bb4b882ea124..f4f534052757 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;
 }
 
@@ -1577,15 +1592,6 @@  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));
@@ -1599,7 +1605,6 @@  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();
 
@@ -1615,6 +1620,8 @@  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);