KVM: arm64: Allow guests with >48-bit IPA size on FEAT_LPA2 systems

With all the page-table infrastructure in place, we can finally increase
the maximum permisable IPA size to 52-bits on 4KB and 16KB page systems
that have FEAT_LPA2.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231127111737.1897081-11-ryan.roberts@arm.com

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 5bb4de162cab5df9ff443e3c37b3917f444944a3..68d1d05672bd4fea76329c936291f9b9c37cc5d3 100644 (file)
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -280,12 +280,11 @@ int __init kvm_set_ipa_limit(void)
        parange = cpuid_feature_extract_unsigned_field(mmfr0,
                                ID_AA64MMFR0_EL1_PARANGE_SHIFT);
        /*
-        * IPA size beyond 48 bits could not be supported
-        * on either 4K or 16K page size. Hence let's cap
-        * it to 48 bits, in case it's reported as larger
-        * on the system.
+        * IPA size beyond 48 bits for 4K and 16K page size is only supported
+        * when LPA2 is available. So if we have LPA2, enable it, else cap to 48
+        * bits, in case it's reported as larger on the system.
         */
-       if (PAGE_SIZE != SZ_64K)
+       if (!kvm_lpa2_is_enabled() && PAGE_SIZE != SZ_64K)
                parange = min(parange, (unsigned int)ID_AA64MMFR0_EL1_PARANGE_48);
 
        /*