arm64: Make kvm-arm.mode={nvhe, protected} an alias of id_aa64mmfr1.vh=0

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 <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-18-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a10b545..41786d2 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2257,6 +2257,9 @@
        kvm-arm.mode=
                        [KVM,ARM] Select one of KVM/arm64's modes of operation.
 
+                       nvhe: Standard nVHE-based mode, without support for
+                             protected guests.
+
                        protected: nVHE-based mode with support for guests whose
                                   state is kept private from the host.
                                   Not valid if the kernel is running in EL2.

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 226bac5..b994d68 100644 (file)
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -45,6 +45,8 @@ static const struct {
        char    alias[FTR_ALIAS_NAME_LEN];
        char    feature[FTR_ALIAS_OPTION_LEN];
 } aliases[] __initconst = {
+       { "kvm-arm.mode=nvhe",          "id_aa64mmfr1.vh=0" },
+       { "kvm-arm.mode=protected",     "id_aa64mmfr1.vh=0" },
 };
 
 static int __init find_field(const char *cmdline,

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 04c4485..597565a 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1966,6 +1966,9 @@ 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);