[PATCH 2/8] x86/boot: Collect AMD speculative features earlier during boot

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

All AMD IBRS-related features are in CPUID.0x80000008.ebx.  Collect them in
early_cpu_init() so init_speculative_mitigations() can use them.

Rework the existing logic structure to fill in c->extended_cpuid_level and
separate out the ambiguous use of ebx in an otherwise 0x80000008-specific
logic block.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
---
 xen/arch/x86/cpu/common.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index 4a163afbfc7e..866f1a516447 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -348,9 +348,13 @@ void __init early_cpu_init(void)
        }
 
        eax = cpuid_eax(0x80000000);
-       if ((eax >> 16) == 0x8000 && eax >= 0x80000008) {
-               ebx = eax >= 0x8000001f ? cpuid_ebx(0x8000001f) : 0;
-               eax = cpuid_eax(0x80000008);
+       if ((eax >> 16) == 0x8000)
+               c->extended_cpuid_level = eax;
+
+       if (c->extended_cpuid_level >= 0x80000008) {
+               cpuid(0x80000008, &eax,
+                     &c->x86_capability[cpufeat_word(X86_FEATURE_CLZERO)],
+                     &ecx, &edx);
 
                paddr_bits = eax & 0xff;
                if (paddr_bits > PADDR_BITS)
@@ -363,10 +367,11 @@ void __init early_cpu_init(void)
                hap_paddr_bits = ((eax >> 16) & 0xff) ?: paddr_bits;
                if (hap_paddr_bits > PADDR_BITS)
                        hap_paddr_bits = PADDR_BITS;
+       }
 
+       if (c->extended_cpuid_level >= 0x8000001f)
                /* Account for SME's physical address space reduction. */
-               paddr_bits -= (ebx >> 6) & 0x3f;
-       }
+               paddr_bits -= (cpuid_ebx(0x8000001f) >> 6) & 0x3f;
 
        if (!(c->x86_vendor & (X86_VENDOR_AMD | X86_VENDOR_HYGON)))
                park_offline_cpus = opt_mce;
-- 
2.11.0