From nobody Sun Feb 8 23:04:18 2026 Received: from out30-118.freemail.mail.aliyun.com (out30-118.freemail.mail.aliyun.com [115.124.30.118]) (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 6E44636C0B2; Mon, 2 Feb 2026 14:07:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.118 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770041264; cv=none; b=PfdrwvapMz20a/9C/coEpIN72cYIFdIhtViQHQYX/nUKQEhvMO/m99Kd7eNysIlvk/wBuY0NcMXaJnFz792/zcaG4nWtQAq6VeaWxlBAzzE4DLe34dXb0ZGTSbIJgi88KspUSJiIfrBkV4kyDnK/Y7z6uwTNzGkTUlpKhHyWBkk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770041264; c=relaxed/simple; bh=EMVTon8oOJKd5XZtb/x9bSjvelR9VX/LOOPvrfVdK3Q=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=q+vxbN7jhs4e7gT1PpA5DQH7fOx8cOe9ph94ohLQc7b4NGot2onlP1gfQdKsOsFGQDgjr9FF6DqXEc4+q9NgBbdW5kVyfPzoCsAg+eMf+Jm4V9U6tpTyVQtmIkJ/dfubfZHPkyYAlvJkNM4SDkTP3a/phYvl3UV9EXH7w9aSqf0= 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=r5YbnuHp; arc=none smtp.client-ip=115.124.30.118 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="r5YbnuHp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1770041258; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=xL+lY+t7zetS6qr1sGNBiYnMdBqphOvpSAPSUtqTssc=; b=r5YbnuHpUDEaCHdfaQ0a8M8kS8VS/FHtzPcAT/8tl73BQZPRwT5///og76+fwV+y2KHvmSQ9WWzy/TSmCtKWM/Ml30oYGUPhz94PXe3hAX3e0xeQbHN7/tu+I9XaHqs65nyXOEEqTKCG5xDMmAJJ2yJEya4s20pGsscFh6ovlkM= Received: from localhost.localdomain(mailfrom:fangyu.yu@linux.alibaba.com fp:SMTPD_---0WyO62XS_1770041255 cluster:ay36) by smtp.aliyun-inc.com; Mon, 02 Feb 2026 22:07:37 +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, ajones@ventanamicro.com, rkrcmar@ventanamicro.com, 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 v4 3/4] RISC-V: KVM: add KVM_CAP_RISCV_SET_HGATP_MODE Date: Mon, 2 Feb 2026 22:07:15 +0800 Message-Id: <20260202140716.34323-4-fangyu.yu@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260202140716.34323-1-fangyu.yu@linux.alibaba.com> References: <20260202140716.34323-1-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 | 20 ++++++++++++++++++-- include/uapi/linux/kvm.h | 1 + 3 files changed, 46 insertions(+), 2 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 01a3abef8abb..1a0c5ddacae8 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. + +``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. + +The returned bitmask uses the following bit positions:: + + bit 0: HGATP.MODE =3D SV39X4 + bit 1: HGATP.MODE =3D SV48X4 + bit 2: HGATP.MODE =3D SV57X4 + 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..3bbbcb6a17a6 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 +215,25 @@ 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: +#ifdef CONFIG_64BIT + if (!kvm_riscv_hgatp_mode_is_valid(cap->args[0])) + return -EINVAL; + + if (kvm->created_vcpus || !kvm_are_all_memslots_empty(kvm)) + return -EBUSY; + + 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