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

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

[Mostafa Saleh]

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@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>

Signed-off-by: Mostafa Saleh <smostafa@google.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

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

[Marc Zyngier]

On Fri, 25 Oct 2024 09:32:59 +0000, Mostafa Saleh wrote:
> 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.
> 
> [...]

Applied to next, thanks!

[1/1] Documentation: Update the behaviour of "kvm-arm.mode"
      commit: e8440c1e2d23a9ca5e0af1a18be637cbd5a5d44f

Cheers,

	M.
-- 
Without deviation from the norm, progress is not possible.