From b6a68b97af23cc75781bed38221ce73144ac2e39 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Fri, 1 Oct 2021 18:05:53 +0100 Subject: KVM: arm64: Allow KVM to be disabled from the command line Although KVM can be compiled out of the kernel, it cannot be disabled at runtime. Allow this possibility by introducing a new mode that will prevent KVM from initialising. This is useful in the (limited) circumstances where you don't want KVM to be available (what is wrong with you?), or when you want to install another hypervisor instead (good luck with that). Reviewed-by: David Brazdil Acked-by: Will Deacon Acked-by: Suzuki K Poulose Signed-off-by: Marc Zyngier Reviewed-by: Andrew Scull Link: https://lore.kernel.org/r/20211001170553.3062988-1-maz@kernel.org --- Documentation/admin-guide/kernel-parameters.txt | 2 ++ 1 file changed, 2 insertions(+) (limited to 'Documentation/admin-guide/kernel-parameters.txt') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 91ba391f9b32..f268731a3d4d 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2365,6 +2365,8 @@ kvm-arm.mode= [KVM,ARM] Select one of KVM/arm64's modes of operation. + none: Forcefully disable KVM. + nvhe: Standard nVHE-based mode, without support for protected guests. -- cgit v1.2.3 From 53e8ce137f7b34bd7a54429d18e0d0e5f56f54e8 Mon Sep 17 00:00:00 2001 From: Alexandru Elisei Date: Mon, 11 Oct 2021 16:38:35 +0100 Subject: Documentation: admin-guide: Document side effects when pKVM is enabled Recent changes to KVM for arm64 has made it impossible for the host to hibernate or use kexec when protected mode is enabled via the kernel command line. There are people who rely on kexec (for example, developers who use kexec as a quick way to test a new kernel), let's document this change in behaviour, so it doesn't catch them by surprise and we have a place to point people to if it does. Signed-off-by: Alexandru Elisei Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20211011153835.291147-1-alexandru.elisei@arm.com --- Documentation/admin-guide/kernel-parameters.txt | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'Documentation/admin-guide/kernel-parameters.txt') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 91ba391f9b32..741e33fd444a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2372,7 +2372,9 @@ state is kept private from the host. Not valid if the kernel is running in EL2. - Defaults to VHE/nVHE based on hardware support. + Defaults to VHE/nVHE based on hardware support. Setting + mode to "protected" will disable kexec and hibernation + for the host. kvm-arm.vgic_v3_group0_trap= [KVM,ARM] Trap guest accesses to GICv3 group-0 -- cgit v1.2.3