KVM: arm64: Don't constrain maximum IPA size based on host configuration

Now that the guest stage-2 page-tables are managed independently from
the host stage-1 page-tables, we can avoid constraining the IPA size
based on the host and instead limit it only based on the PARange field
of the ID_AA64MMFR0 register.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200911132529.19844-22-will@kernel.org

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index ee33875..2202b71 100644 (file)
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -339,7 +339,7 @@ u32 get_kvm_ipa_limit(void)
 
 int kvm_set_ipa_limit(void)
 {
-       unsigned int ipa_max, pa_max, va_max, parange, tgran_2;
+       unsigned int parange, tgran_2;
        u64 mmfr0;
 
        mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
@@ -376,39 +376,11 @@ int kvm_set_ipa_limit(void)
                break;
        }
 
-       pa_max = id_aa64mmfr0_parange_to_phys_shift(parange);
-
-       /* Clamp the IPA limit to the PA size supported by the kernel */
-       ipa_max = (pa_max > PHYS_MASK_SHIFT) ? PHYS_MASK_SHIFT : pa_max;
-       /*
-        * Since our stage2 table is dependent on the stage1 page table code,
-        * we must always honor the following condition:
-        *
-        *  Number of levels in Stage1 >= Number of levels in Stage2.
-        *
-        * So clamp the ipa limit further down to limit the number of levels.
-        * Since we can concatenate upto 16 tables at entry level, we could
-        * go upto 4bits above the maximum VA addressable with the current
-        * number of levels.
-        */
-       va_max = PGDIR_SHIFT + PAGE_SHIFT - 3;
-       va_max += 4;
-
-       if (va_max < ipa_max)
-               ipa_max = va_max;
-
-       /*
-        * If the final limit is lower than the real physical address
-        * limit of the CPUs, report the reason.
-        */
-       if (ipa_max < pa_max)
-               pr_info("kvm: Limiting the IPA size due to kernel %s Address limit\n",
-                       (va_max < pa_max) ? "Virtual" : "Physical");
-
-       WARN(ipa_max < KVM_PHYS_SHIFT,
-            "KVM IPA limit (%d bit) is smaller than default size\n", ipa_max);
-       kvm_ipa_limit = ipa_max;
-       kvm_info("IPA Size Limit: %dbits\n", kvm_ipa_limit);
+       kvm_ipa_limit = id_aa64mmfr0_parange_to_phys_shift(parange);
+       WARN(kvm_ipa_limit < KVM_PHYS_SHIFT,
+            "KVM IPA Size Limit (%d bits) is smaller than default size\n",
+            kvm_ipa_limit);
+       kvm_info("IPA Size Limit: %d bits\n", kvm_ipa_limit);
 
        return 0;
 }