linux-kernel - [PATCH v3] Documentation: Update the behaviour of "kvm-arm.mode"

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20241025093259.2216093-1-smostafa@google.com>
Date: Fri, 25 Oct 2024 09:32:59 +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 v3] 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>

---
v3: Reword as Marc suggested.

v2: Update nested value also
---
 Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1518343bbe22..ed92e207e9a0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2740,17 +2740,21 @@
 			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.
+			protected: Mode with support for guests whose state is
+				   kept private from the host, using VHE or
+				   nVHE depending on HW support.
 
 			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
-			for the host. "nested" is experimental and should be
-			used with extreme caution.
+			for the host. To force nVHE on VHE hardware, add
+			"arm64_sw.hvhe=0 id_aa64mmfr1.vh=0" to the
+			command-line.
+			"nested" is experimental and should be used with
+			extreme caution.
 
 	kvm-arm.vgic_v3_group0_trap=
 			[KVM,ARM,EARLY] Trap guest accesses to GICv3 group-0
-- 
2.47.0.163.g1226f6d8fa-goog