Thread (49 messages) 49 messages, 6 authors, 2020-12-02

Re: [PATCH v3 06/23] kvm: arm64: Add kvm-arm.protected early kernel parameter

From: David Brazdil <hidden>
Date: 2020-12-01 13:20:05
Also in: kvmarm, linux-doc, lkml

Hey Sudeep,
quoted
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 526d65d8573a..06c89975c29c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2259,6 +2259,11 @@
 			for all guests.
 			Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
 
+	kvm-arm.protected=
+			[KVM,ARM] Allow spawning protected guests whose state
+			is kept private from the host. Only valid for non-VHE.
+			Default is 0 (disabled).
+
Sorry for being pedantic. Can we reword this to say valid for
!CONFIG_ARM64_VHE ? I read this as valid only for non-VHE hardware, it may
be just me, but if you agree please update so that it doesn't give remote
idea that it is not valid on VHE enabled hardware.

I was trying to run this on the hardware and was trying to understand the
details on how to do that.
I see what you're saying, but !CONFIG_ARM64_VHE isn't accurate either. The
option makes sense if:
  1) all cores booted in EL2
     == is_hyp_mode_available()
  2) ID_AA64MMFR1_EL1.VH=0 or !CONFIG_ARM64_VHE
     == !is_kernel_in_hyp_mode()

The former feels implied for KVM, the latter could be 'Valid if the kernel
is running in EL1'? WDYT?

-David

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