[PATCH v16 12/45] KVM: arm64: CCA: Check for LPA2 support
From: Steven Price <steven.price@arm.com>
Date: 2026-08-03 13:45:14
Also in:
kvm, kvmarm, linux-coco, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
If KVM has enabled LPA2 support then check that the RMM also supports it. If there is a mismatch then disable support for realm guests as the VMM may attempt to create a guest which is incompatible with the RMM. Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Steven Price <steven.price@arm.com> --- v15: * Extend rmi_has_feature() to take the register number and check the presence of SHA-256 support which is default. v13: * New patch --- arch/arm64/kvm/rmi.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)
diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c
index 384991d69f78..247c4f033945 100644
--- a/arch/arm64/kvm/rmi.c
+++ b/arch/arm64/kvm/rmi.c@@ -5,9 +5,31 @@ #include <linux/kvm_host.h> +#include <asm/kvm_pgtable.h> #include <asm/rmi_cmds.h> #include <asm/virt.h> +static bool rmi_has_feature(int reg, unsigned long feature) +{ + return !!u64_get_bits(rmi_feat_reg(reg), feature); +} + +static int rmm_check_features(void) +{ + if (kvm_lpa2_is_enabled() && + !rmi_has_feature(0, RMI_FEATURE_REGISTER_0_LPA2)) { + kvm_err("RMM doesn't support LPA2\n"); + return -ENXIO; + } + + if (!rmi_has_feature(1, RMI_FEATURE_REGISTER_1_HASH_SHA_256)) { + kvm_err("RMM doesn't support SHA-256 measurements\n"); + return -ENXIO; + } + + return 0; +} + void kvm_init_rmi(void) { /*
@@ -20,5 +42,8 @@ void kvm_init_rmi(void) if (!is_rmi_available()) return; + if (rmm_check_features()) + return; + /* Future patch will enable static branch kvm_rmi_is_available */ }
--
2.43.0