From nobody Sun Feb 8 23:04:02 2026 Received: from out30-99.freemail.mail.aliyun.com (out30-99.freemail.mail.aliyun.com [115.124.30.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 82073392827; Wed, 4 Feb 2026 13:45:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.99 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770212736; cv=none; b=nHFzo9WfUF8T0EsbSL8XHkScJnFZZpEcCRhjkFwlC3/KP6pbkx7wB6O1MV3Vulg8f5Zabvf9TD1cp8nkYQu7TfclwYFXgEK9/1ltzlK/fWQLQOqjrbtN2XxBV8KyurGsmovq0y/qWczq+fUpiN5ChUuULBGwiKyj3hcLkFnFT7k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770212736; c=relaxed/simple; bh=6AoUWFoe1qTdaPzHfdR8hNXmzBqZ37rlpHoBFd6gM1M=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=T6z11rme227JXTTxJQeYbpF6aPt5Zstu+FNfNzL22wmfbyTUtPnZERwhuI4AMMJYzVmv/bKtxvkmlw1EJsPD8aAIpdbRzE38bAd8xXbXp2qpkN2k9pkhngK9Wf1fUnmQNbI9qi5d1aQS+/Pl083ly32tVnhRoxsZ3acc7ZXmYTk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=p8L3brfY; arc=none smtp.client-ip=115.124.30.99 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="p8L3brfY" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1770212724; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=5R42yBenU3WsqPgksKfBN/gXqqDJrrdf2h4U39oXsd8=; b=p8L3brfYKi6VejGdkPtQhQstAeQ2lIpJfXKDrlXjdyndWuit/nXBGn/lM605LeSCM1tkTZy8Rs0IReLS0FJr1+VbCm3boFg2JrCNIA6Zelr6QTz++3/XotT3TYsjcaA11jKGNDKCWMW6GR0FHpfmozvARvKAauXaLgtiR7l5e7A= Received: from localhost.localdomain(mailfrom:fangyu.yu@linux.alibaba.com fp:SMTPD_---0WyXBzAg_1770212721 cluster:ay36) by smtp.aliyun-inc.com; Wed, 04 Feb 2026 21:45:22 +0800 From: fangyu.yu@linux.alibaba.com To: pbonzini@redhat.com, corbet@lwn.net, anup@brainfault.org, atish.patra@linux.dev, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr Cc: guoren@kernel.org, radim.krcmar@oss.qualcomm.com, andrew.jones@oss.qualcomm.com, linux-doc@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Fangyu Yu Subject: [PATCH v5 3/3] RISC-V: KVM: add KVM_CAP_RISCV_SET_HGATP_MODE Date: Wed, 4 Feb 2026 21:45:07 +0800 Message-Id: <20260204134507.33912-4-fangyu.yu@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260204134507.33912-1-fangyu.yu@linux.alibaba.com> References: <20260204134507.33912-1-fangyu.yu@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Fangyu Yu Add a VM capability that allows userspace to select the G-stage page table format by setting HGATP.MODE on a per-VM basis. Userspace enables the capability via KVM_ENABLE_CAP, passing the requested HGATP.MODE in args[0]. The request is rejected with -EINVAL if the mode is not supported by the host, and with -EBUSY if the VM has already been committed (e.g. vCPUs have been created or any memslot is populated). KVM_CHECK_EXTENSION(KVM_CAP_RISCV_SET_HGATP_MODE) returns a bitmask of the HGATP.MODE formats supported by the host. Signed-off-by: Fangyu Yu --- Documentation/virt/kvm/api.rst | 27 +++++++++++++++++++++++++++ arch/riscv/kvm/vm.c | 19 +++++++++++++++++-- include/uapi/linux/kvm.h | 1 + 3 files changed, 45 insertions(+), 2 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 01a3abef8abb..62dc120857c1 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -8765,6 +8765,33 @@ helpful if user space wants to emulate instructions = which are not This capability can be enabled dynamically even if VCPUs were already created and are running. =20 +7.47 KVM_CAP_RISCV_SET_HGATP_MODE +--------------------------------- + +:Architectures: riscv +:Type: VM +:Parameters: args[0] contains the requested HGATP mode +:Returns: + - 0 on success. + - -EINVAL if args[0] is outside the range of HGATP modes supported by the + hardware. + - -EBUSY if vCPUs have already been created for the VM, if the VM has any + non-empty memslots. + +This capability allows userspace to explicitly select the HGATP mode for +the VM. The selected mode must be supported by both KVM and hardware. This +capability must be enabled before creating any vCPUs or memslots. + +If this capability is not enabled, KVM will select the default HGATP mode +automatically. The default is the highest HGATP.MODE value supported by +hardware. + +``KVM_CHECK_EXTENSION(KVM_CAP_RISCV_SET_HGATP_MODE)`` returns a bitmask of +HGATP.MODE values supported by the host. A return value of 0 indicates that +the capability is not supported. Supported-mode bitmask use HGATP.MODE +encodings as defined by the RISC-V privileged specification, such as Sv39x4 +corresponds to HGATP.MODE=3D8, so userspace should test bitmask & BIT(8). + 8. Other capabilities. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c index 4b2156df40fc..7d1e1d257df5 100644 --- a/arch/riscv/kvm/vm.c +++ b/arch/riscv/kvm/vm.c @@ -202,6 +202,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long = ext) case KVM_CAP_VM_GPA_BITS: r =3D kvm_riscv_gstage_gpa_bits(&kvm->arch); break; + case KVM_CAP_RISCV_SET_HGATP_MODE: + r =3D kvm_riscv_get_hgatp_mode_mask(); + break; default: r =3D 0; break; @@ -212,12 +215,24 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, lon= g ext) =20 int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) { + if (cap->flags) + return -EINVAL; + switch (cap->cap) { case KVM_CAP_RISCV_MP_STATE_RESET: - if (cap->flags) - return -EINVAL; kvm->arch.mp_state_reset =3D true; return 0; + case KVM_CAP_RISCV_SET_HGATP_MODE: + if (!kvm_riscv_hgatp_mode_is_valid(cap->args[0])) + return -EINVAL; + + if (kvm->created_vcpus || !kvm_are_all_memslots_empty(kvm)) + return -EBUSY; +#ifdef CONFIG_64BIT + kvm->arch.kvm_riscv_gstage_pgd_levels =3D + 3 + cap->args[0] - HGATP_MODE_SV39X4; +#endif + return 0; default: return -EINVAL; } diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index dddb781b0507..00c02a880518 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -974,6 +974,7 @@ struct kvm_enable_cap { #define KVM_CAP_GUEST_MEMFD_FLAGS 244 #define KVM_CAP_ARM_SEA_TO_USER 245 #define KVM_CAP_S390_USER_OPEREXEC 246 +#define KVM_CAP_RISCV_SET_HGATP_MODE 247 =20 struct kvm_irq_routing_irqchip { __u32 irqchip; --=20 2.50.1