There is some value in keeping the IPA space small, as it reduces
the size of the stage-2 page tables.
Let's compute the required space at VM creation time, and inform
the kernel of our requirements.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arm/aarch64/kvm.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
diff --git a/arm/aarch64/kvm.c b/arm/aarch64/kvm.c
index d03a27f2..4e66a22e 100644
--- a/arm/aarch64/kvm.c
+++ b/arm/aarch64/kvm.c
@@ -3,6 +3,7 @@
#include <asm/image.h>
#include <linux/byteorder.h>
+#include <kvm/util.h>
/*
* Return the TEXT_OFFSET value that the guest kernel expects. Note
@@ -59,5 +60,22 @@ int kvm__arch_get_ipa_limit(struct kvm *kvm)
int kvm__get_vm_type(struct kvm *kvm)
{
- return KVM_VM_TYPE_ARM_IPA_SIZE(kvm__arch_get_ipa_limit(kvm));
+ unsigned int ipa_bits, max_ipa_bits;
+ unsigned long max_ipa;
+
+ /* If we're running on an old kernel, use 0 as the VM type */
+ max_ipa_bits = kvm__arch_get_ipa_limit(kvm);
+ if (!max_ipa_bits)
+ return 0;
+
+ /* Otherwise, compute the minimal required IPA size */
+ max_ipa = ARM_MEMORY_AREA + kvm->cfg.ram_size - 1;
+ ipa_bits = max(32, fls_long(max_ipa));
+ pr_debug("max_ipa %lx ipa_bits %d max_ipa_bits %d",
+ max_ipa, ipa_bits, max_ipa_bits);
+
+ if (ipa_bits > max_ipa_bits)
+ die("Memory too large for this system (needs %d bits, %d available)", ipa_bits, max_ipa_bits);
+
+ return KVM_VM_TYPE_ARM_IPA_SIZE(ipa_bits);
}
--
2.30.2
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