linux-kernel - [PATCH v2] Documentation: Update the behaviour of "kvm-arm.mode"

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Message-ID: <20241024160614.1894599-1-smostafa@google.com>
Date: Thu, 24 Oct 2024 16:06:14 +0000
From: Mostafa Saleh <smostafa@...gle.com>
To: linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org
Cc: corbet@....net, Mostafa Saleh <smostafa@...gle.com>, Will Deacon <will@...nel.org>, 
	Marc Zyngier <maz@...nel.org>
Subject: [PATCH v2] Documentation: Update the behaviour of "kvm-arm.mode"

Commit 5053c3f0519c ("KVM: arm64: Use hVHE in pKVM by default on CPUs with
VHE support") modified the behaviour of "kvm-arm.mode=protected" without
the updating the kernel parameters doc.

Update it to match the current implementation.

Also, update required architecture version for nested virtualization as
suggested by Marc.

Cc: Will Deacon <will@...nel.org>
Cc: Marc Zyngier <maz@...nel.org>

Signed-off-by: Mostafa Saleh <smostafa@...gle.com>

---
v2: Update nested value also
---
 Documentation/admin-guide/kernel-parameters.txt | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1518343bbe22..d5b771e5cb5b 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2740,12 +2740,16 @@
 			nvhe: Standard nVHE-based mode, without support for
 			      protected guests.
 
-			protected: nVHE-based mode with support for guests whose
+			protected: hVHE-based mode with support for guests whose
 				   state is kept private from the host.
+				   In case hVHE is not supported in hardware, it will
+				   boot with protected nVHE.
+				   nVHE protected mode can still be forced on VHE systems
+				   using "kvm_arm.mode=protected arm64_sw.hvhe=0 id_aa64mmfr1.vh=0"
 
 			nested: VHE-based mode with support for nested
-				virtualization. Requires at least ARMv8.3
-				hardware.
+				virtualization. Requires at least ARMv8.4
+				hardware (with FEAT_NV2).
 
 			Defaults to VHE/nVHE based on hardware support. Setting
 			mode to "protected" will disable kexec and hibernation
-- 
2.47.0.105.g07ac214952-goog