[PATCH 3/3][Do not merge] kvmtool: arm64: Configure VM with the minimal required IPA space
From: Marc Zyngier <maz@kernel.org>
Date: 2021-03-09 16:41:10
Subsystem:
the rest · Maintainer:
Linus Torvalds
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@kernel.org> --- 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 c4f81d0..981cb42 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__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 ipa_bits; }
--
2.30.0
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