On 12/9/21 22:47, Sean Christopherson wrote:
+ /*
+ * Otherwise it's at the top of the physical address
+ * space, possibly reduced due to SME by bits 11:6 of
+ * CPUID[0x8000001f].EBX.
+ */
+ eax = 0x80000008;
+ cpuid(&eax, &ebx, &ecx, &edx);
Should't this check 0x80000000.eax >= 0x80000008 first? Or do we just accept
failure if family==0x17 and there's no 0x80000008? One paranoid option would be
to use the pre-fam17 value, e.g.
/* Before family 17h, the HyperTransport area is just below 1T. */
ht_gfn = (1 << 28) - num_ht_pages;
if (x86_family(eax) < 0x17)
goto out;
eax = 0x80000000;
cpuid(&eax, &ebx, &ecx, &edx);
max_ext_leaf = eax;
/* Use the old, conservative value if MAXPHYADDR isn't enumerated. */
if (max_ext_leaf < 0x80000008)
goto out;
Yes, this works for me too. Though in practice I don't think any 64-bit
machine ever existed without 0x80000008 (you need it to decide what's a
canonical address and what isn't), so that would have to be a 32-bit
fam17h machine.
Paolo
/* comment */
eax = 0x80000008;
cpuid(&eax, &ebx, &ecx, &edx);
max_pfn = (1ULL << ((eax & 255) - vm->page_shift)) - 1;
if (max_ext_leaf >= 0x8000001f) {
<adjust>
}
ht_gfn = max_pfn - num_ht_pages;
out:
return min(max_gfn, ht_gfn - 1);
+ max_pfn = (1ULL << ((eax & 255) - vm->page_shift)) - 1;
LOL, "& 255", you just couldn't resist, huh? My version of Rami Code only goes
up to 15.:-)
