[SRU][J:linux-gcp][PATCH 1/2] x86/cpu: Allow reducing x86_phys_bits during early_identify_cpu()

[Ian Whitfield]

From: Paolo Bonzini <pbonzini at redhat.com>

BugLink: https://bugs.launchpad.net/bugs/2097811

In commit fbf6449f84bf ("x86/sev-es: Set x86_virt_bits to the correct
value straight away, instead of a two-phase approach"), the initialization
of c->x86_phys_bits was moved after this_cpu->c_early_init(c).  This is
incorrect because early_init_amd() expected to be able to reduce the
value according to the contents of CPUID leaf 0x8000001f.

Fortunately, the bug was negated by init_amd()'s call to early_init_amd(),
which does reduce x86_phys_bits in the end.  However, this is very
late in the boot process and, most notably, the wrong value is used for
x86_phys_bits when setting up MTRRs.

To fix this, call get_cpu_address_sizes() as soon as X86_FEATURE_CPUID is
set/cleared, and c->extended_cpuid_level is retrieved.

Fixes: fbf6449f84bf ("x86/sev-es: Set x86_virt_bits to the correct value straight away, instead of a two-phase approach")
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
Signed-off-by: Dave Hansen <dave.hansen at linux.intel.com>
Cc:stable at vger.kernel.org
Link: https://lore.kernel.org/all/20240131230902.1867092-2-pbonzini%40redhat.com
(cherry picked from commit 9a458198eba98b7207669a166e64d04b04cb651b)
Signed-off-by: Ian Whitfield <ian.whitfield at canonical.com>
---
 arch/x86/kernel/cpu/common.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 4354ae136d57..f61f44895667 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1550,6 +1550,7 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 		get_cpu_cap(c);
 		get_cpu_address_sizes(c);
 		setup_force_cpu_cap(X86_FEATURE_CPUID);
+		get_cpu_address_sizes(c);
 		cpu_parse_early_param();
 
 		if (this_cpu->c_early_init)
@@ -1562,6 +1563,7 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 			this_cpu->c_bsp_init(c);
 	} else {
 		setup_clear_cpu_cap(X86_FEATURE_CPUID);
+		get_cpu_address_sizes(c);
 	}
 
 	setup_force_cpu_cap(X86_FEATURE_ALWAYS);
-- 
2.43.0