commit cce5a4f6ae9b1db634245521e7967cc605e0bedc
author Alexandru Elisei <alexandru.elisei@arm.com> Thu Jun 16 14:48:21 2022 +0100
committer Will Deacon <will@kernel.org> Fri Jul 01 16:08:06 2022 +0100
tree 9b3940c81295537378f4786cc641d1c81b16ea9c
parent abe3f28a9c0700837aca75887f0cd65c6371e2e4

arm/arm64: Fail if RAM size is too large for 32-bit guests

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@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-and-Tested-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20220616134828.129006-6-alexandru.elisei@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

arm/aarch32/kvm.c

diff --git a/arm/aarch32/kvm.c b/arm/aarch32/kvm.c
index ae33ac9..9d68d7a 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);
+	}
 }

arm/aarch64/kvm.c

diff --git a/arm/aarch64/kvm.c b/arm/aarch64/kvm.c
index ca348f1..2134528 100644
--- a/arm/aarch64/kvm.c
+++ b/arm/aarch64/kvm.c
@@ -39,6 +39,11 @@
 
 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);
+	}
 }
 
 /*

arm/kvm.c

diff --git a/arm/kvm.c b/arm/kvm.c
index c591300..af0feae 100644
--- a/arm/kvm.c
+++ b/arm/kvm.c
@@ -65,7 +65,7 @@
 	 * 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);