[PATCH v4 kvmtool 05/12] arm/arm64: Fail if RAM size is too large for 32-bit guests

[Alexandru Elisei]

For 64-bit guests, kvmtool exists with an error in kvm__get_vm_type() if
the memory size is larger than what KVM supports. For 32-bit guests, the
RAM size is silently rounded down to ARM_LOMAP_MAX_MEMORY in
kvm__arch_init().

Be consistent and exit with an error when the user has configured the
wrong RAM size for 32-bit guests.

Reviewed-by: Andre Przywara <andre.przywara at arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei at arm.com>
---
 arm/aarch32/kvm.c | 4 ++++
 arm/aarch64/kvm.c | 5 +++++
 arm/kvm.c         | 2 +-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arm/aarch32/kvm.c b/arm/aarch32/kvm.c
index ae33ac92479a..9d68d7a15ee2 100644
--- a/arm/aarch32/kvm.c
+++ b/arm/aarch32/kvm.c
@@ -2,4 +2,8 @@
 
 void kvm__arch_validate_cfg(struct kvm *kvm)
 {
+	if (kvm->cfg.ram_size > ARM_LOMAP_MAX_MEMORY) {
+		die("RAM size 0x%llx exceeds maximum allowed 0x%llx",
+		    kvm->cfg.ram_size, ARM_LOMAP_MAX_MEMORY);
+	}
 }
diff --git a/arm/aarch64/kvm.c b/arm/aarch64/kvm.c
index ca348f118a56..2134528bf7f2 100644
--- a/arm/aarch64/kvm.c
+++ b/arm/aarch64/kvm.c
@@ -39,6 +39,11 @@ int vcpu_affinity_parser(const struct option *opt, const char *arg, int unset)
 
 void kvm__arch_validate_cfg(struct kvm *kvm)
 {
+	if (kvm->cfg.arch.aarch32_guest &&
+	    kvm->cfg.ram_size > ARM_LOMAP_MAX_MEMORY) {
+		die("RAM size 0x%llx exceeds maximum allowed 0x%llx",
+		    kvm->cfg.ram_size, ARM_LOMAP_MAX_MEMORY);
+	}
 }
 
 /*
diff --git a/arm/kvm.c b/arm/kvm.c
index c5913000e1ed..af0feae495d7 100644
--- a/arm/kvm.c
+++ b/arm/kvm.c
@@ -65,7 +65,7 @@ void kvm__arch_init(struct kvm *kvm, const char *hugetlbfs_path, u64 ram_size)
 	 * If using THP, then our minimal alignment becomes 2M.
 	 * 2M trumps 64K, so let's go with that.
 	 */
-	kvm->ram_size = min(ram_size, (u64)ARM_MAX_MEMORY(kvm));
+	kvm->ram_size = ram_size;
 	kvm->arch.ram_alloc_size = kvm->ram_size + SZ_2M;
 	kvm->arch.ram_alloc_start = mmap_anon_or_hugetlbfs(kvm, hugetlbfs_path,
 						kvm->arch.ram_alloc_size);
-- 
2.36.1