[3/3] KVM: arm64: Fix boot warning with kvm-arm.mode=nvhe on !FEAT_E2H0 platforms

Commit Message

Yicong Yang March 29, 2025, 3:44 a.m. UTC

From: Yicong Yang <[e-mail]>

If platforms don't support FEAT_E2H0, HCR_EL2.E2H is RES1 and nVHE is
not available. The warning in early_kvm_mode_cfg() will be triggered
if boot with kvm-arm.mode=nvhe and no indication for this. Fix this by
skipping the non-VHE checking on !FEAT_E2H0 platform.

Since this should only affect the "nvhe" mode, move "nested" mode check
ahead to avoid being affected.

Signed-off-by: Yicong Yang <[e-mail]>
---
 arch/arm64/kvm/arm.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

Patch

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 68fec8c95fee..a0c0bd936a53 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2905,6 +2905,11 @@  static int __init early_kvm_mode_cfg(char *arg)
 		return 0;
 	}
 
+	if (strcmp(arg, "nested") == 0 && !WARN_ON(!is_kernel_in_hyp_mode())) {
+		kvm_mode = KVM_MODE_NV;
+		return 0;
+	}
+
 	if (strcmp(arg, "protected") == 0) {
 		if (!is_kernel_in_hyp_mode())
 			kvm_mode = KVM_MODE_PROTECTED;
@@ -2914,13 +2919,16 @@  static int __init early_kvm_mode_cfg(char *arg)
 		return 0;
 	}
 
-	if (strcmp(arg, "nvhe") == 0 && !WARN_ON(is_kernel_in_hyp_mode())) {
+	/* If system doesn't support FEAT_E2H0, nVHE host is not available */
+	if (cpu_has_e2h_res1()) {
+		WARN_ON(!is_kernel_in_hyp_mode());
 		kvm_mode = KVM_MODE_DEFAULT;
+		pr_warn_once("FEAT_E2H0 not supported. Ignoring kvm-arm.mode\n");
 		return 0;
 	}
 
-	if (strcmp(arg, "nested") == 0 && !WARN_ON(!is_kernel_in_hyp_mode())) {
-		kvm_mode = KVM_MODE_NV;
+	if (strcmp(arg, "nvhe") == 0 && !WARN_ON(is_kernel_in_hyp_mode())) {
+		kvm_mode = KVM_MODE_DEFAULT;
 		return 0;
 	}