Subject: [PATCH 15/17] arm64: Make kvm-arm.mode={nvhe, protected} an alias of id_aa64mmfr1.vh=0

From: Marc Zyngier <[email-masked]>
Date: Mon, 28 Dec 2020 10:49:56 +0000

Admitedly, passing id_aa64mmfr1.vh=0 on the command-line isn't
that easy to understand, and it is likely that users would much
prefer write "kvm-arm.mode=nvhe", or "...=protected".

So here you go. This has the added advantage that we can now
always honor the "kvm-arm.mode=protected" option, even when
booting on a VHE system.

Signed-off-by: Marc Zyngier <[email-masked]>
---
 arch/arm64/kernel/idreg-override.c | 2 ++
 arch/arm64/kvm/arm.c               | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 8f64100e0b1b..5296cd77895b 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -41,6 +41,8 @@ static const struct {
 	const char * const	alias;
 	const char * const	feature;
 } aliases[] __initdata = {
+	{ "kvm-arm.mode=nvhe",		"id_aa64mmfr1.vh=0" },
+	{ "kvm-arm.mode=protected",	"id_aa64mmfr1.vh=0" },
 };
 
 static int __init find_field(const char *cmdline, const struct reg_desc *reg,
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 71a49eae9ea0..24aa57ee057c 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1962,6 +1962,9 @@ static int __init early_kvm_mode_cfg(char *arg)
 		return 0;
 	}
 
+	if (strcmp(arg, "nvhe") == 0 && !WARN_ON(is_kernel_in_hyp_mode()))
+		return 0;
+
 	return -EINVAL;
 }
 early_param("kvm-arm.mode", early_kvm_mode_cfg);
-- 
2.29.2

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