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From: Fuad Tabba <fuad.tabba@linux.dev>
To: Marc Zyngier <maz@kernel.org>, Oliver Upton <oupton@kernel.org>,
	kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
	Steffen Eiden <seiden@linux.ibm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Vincent Donnefort <vdonnefort@google.com>,
	Quentin Perret <qperret@google.com>,
	Fuad Tabba <tabba@google.com>,
	kvm@vger.kernel.org
Subject: [PATCH] KVM: arm64: Fix the KVM_ARM_PREFERRED_TARGET documentation
Date: Mon, 31 Aug 2026 17:28:15 +0100	[thread overview]
Message-ID: <20260831162815.269851-1-fuad.tabba@linux.dev> (raw)

KVM_ARM_PREFERRED_TARGET has never set a feature bit: the original arm64
implementation zeroed the bitmap, and kvm_vcpu_preferred_target(), which
only ever zeroed it, was removed by commit 5346f7e13e5e ("KVM: arm64:
Always return generic v8 as the preferred target"). The ENODEV error had
gone earlier still, with commit 08e873cb70f3 ("KVM: arm64: Change the
return type of kvm_vcpu_preferred_target()"). Document what it returns,
that userspace selects vCPU features itself, and drop the error.

No functional change intended.

Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 Documentation/virt/kvm/api.rst | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index e0430cc750c9e..193f3b0ec77d1 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -3600,20 +3600,14 @@ Possible features:
 :Parameters: struct kvm_vcpu_init (out)
 :Returns: 0 on success; -1 on error
 
-Errors:
-
-  ======     ==========================================
-  ENODEV     no preferred target available for the host
-  ======     ==========================================
-
 This queries KVM for preferred CPU target type which can be emulated
 by KVM on underlying host.
 
-The ioctl returns struct kvm_vcpu_init instance containing information
-about preferred CPU target type and recommended features for it.  The
-kvm_vcpu_init->features bitmap returned will have feature bits set if
-the preferred target recommends setting these features, but this is
-not mandatory.
+The ioctl returns a struct kvm_vcpu_init instance containing the
+preferred CPU target type. The kvm_vcpu_init->features bitmap is
+returned empty: userspace selects the vCPU features itself, and their
+availability is reported by the capabilities listed under
+KVM_ARM_VCPU_INIT.
 
 The information returned by this ioctl can be used to prepare an instance
 of struct kvm_vcpu_init for KVM_ARM_VCPU_INIT ioctl which will result in

base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
-- 
2.39.5


                 reply	other threads:[~2026-08-31 16:28 UTC|newest]

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