From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CDA0FC79FBC for ; Fri, 16 Jan 2026 14:30:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=BtIqg7P1kikzkdjOW4yFXSjqADIHCwv6TlsYG9ZlQGs=; b=nPGT0t3AN76mSV voiqQfFJ5oMpczjmdUwDJxTqWz/Vry4JTE54govFzbxKARi+c9fG72ZqyBJ1UGydMutKhklHH2HdB ImKbUHzVHY6CjZRHeXtdUjz0Hf0kFhcRLNT+pijNIuVNeuqmZy5Z9JgV2bEAt46/J90JrcW6HD1y2 3A6nJjb7Igqx5qbNImDkSn06t5YFYDGI63Hr2EKdLNXPTfkKl8NdNKbwbk2kGd6by2mrcoR3k5dql lSA3BGlrHbtK7OwpY5S6DQVpvqUr5Xpsk60st3nIgkd0prPSISchVsrQskpy09TXBbaLRFaASKDeA 1s46RoYi4Q/3EJ4zLl8Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vgkqD-0000000EG5l-2XWN; Fri, 16 Jan 2026 14:30:21 +0000 Received: from out30-112.freemail.mail.aliyun.com ([115.124.30.112]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vgkq8-0000000EG3u-25rI; Fri, 16 Jan 2026 14:30:20 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1768573804; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=XnMbHiZD4Q8ihaJAYTR3qJJVShDyzERVKVSspF7MbMc=; b=eCCJGVPjwitC351Gssj6Rl1CvmVijt/YU7KiHVz82kIRnxdGMb7LKolpqKRXTBoTBCSnR0Oqn1Ic8eAlP8kCDDXRuZ9/ewrU6zXcrcn8F4tedHyUm7MUoR1uF4v3iiwrM9TbKluwa7Q8V5/GXbIYuMN2TY6JxAdLzOs5lfuAAUE= Received: from localhost.localdomain(mailfrom:fangyu.yu@linux.alibaba.com fp:SMTPD_---0WxARSAt_1768573791 cluster:ay36) by smtp.aliyun-inc.com; Fri, 16 Jan 2026 22:29:53 +0800 From: fangyu.yu@linux.alibaba.com To: andrew.jones@oss.qualcomm.com Cc: ajones@ventanamicro.com, alex@ghiti.fr, anup@brainfault.org, aou@eecs.berkeley.edu, atish.patra@linux.dev, corbet@lwn.net, fangyu.yu@linux.alibaba.com, guoren@kernel.org, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, palmer@dabbelt.com, pbonzini@redhat.com, pjw@kernel.org, rkrcmar@ventanamicro.com Subject: Re: Re: [PATCH v2] RISC-V: KVM: add KVM_CAP_RISCV_SET_HGATP_MODE Date: Fri, 16 Jan 2026 22:29:47 +0800 Message-Id: <20260116142947.30520-1-fangyu.yu@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260116_063017_612144_EA676DFF X-CRM114-Status: GOOD ( 20.63 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org >> From: Fangyu Yu >> >> This capability allows userspace to explicitly select the HGATP mode >> for the VM. The selected mode must be less than or equal to the max >> HGATP mode supported by the hardware. This capability must be enabled >> before creating any vCPUs, and can only be set once per VM. >> >> Signed-off-by: Fangyu Yu >> --- >> Documentation/virt/kvm/api.rst | 14 ++++++++++++++ >> arch/riscv/kvm/vm.c | 26 ++++++++++++++++++++++++-- >> include/uapi/linux/kvm.h | 1 + >> 3 files changed, 39 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst >> index 01a3abef8abb..9e17788e3a9d 100644 >> --- a/Documentation/virt/kvm/api.rst >> +++ b/Documentation/virt/kvm/api.rst >> @@ -8765,6 +8765,20 @@ 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. >> >> +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 arg[0] is outside the range of hgatp >> + modes supported by the hardware. >> + >> +This capability allows userspace to explicitly select the HGATP mode for >> +the VM. The selected mode must be less than or equal to the maximum HGATP >> +mode supported by the hardware. This capability must be enabled before >> +creating any vCPUs, and can only be set once per VM. > >I think I would prefer a KVM_CAP_RISCV_SET_MAX_GPA type of capability. The >reason is because, while one of the results of the max-gpa being set will >be to set hgatp, there may be other reasons to track the guest's maximum >physical address too and kvm userspace shouldn't need to think about each >individually. That makes sense, thanks. >> + >> 8. Other capabilities. >> ====================== >> >> diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c >> index 4b2156df40fc..e9275023a73a 100644 >> --- a/arch/riscv/kvm/vm.c >> +++ b/arch/riscv/kvm/vm.c >> @@ -202,6 +202,13 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) >> case KVM_CAP_VM_GPA_BITS: >> r = kvm_riscv_gstage_gpa_bits(&kvm->arch); >> break; >> + case KVM_CAP_RISCV_SET_HGATP_MODE: >> +#ifdef CONFIG_64BIT >> + r = 1; >> +#else/* CONFIG_32BIT */ >> + r = 0; >> +#endif > > r = IS_ENABLED(CONFIG_64BIT) ? 1 : 0; Ack. >> + break; >> default: >> r = 0; >> break; >> @@ -212,12 +219,27 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) >> >> int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) >> { >> + if (cap->flags) >> + return -EINVAL; > >add blank line Ack, will add a blank line after the flags check. > >> switch (cap->cap) { >> case KVM_CAP_RISCV_MP_STATE_RESET: >> - if (cap->flags) >> - return -EINVAL; >> kvm->arch.mp_state_reset = true; >> return 0; >> + case KVM_CAP_RISCV_SET_HGATP_MODE: >> +#ifdef CONFIG_64BIT >> + if (cap->args[0] < HGATP_MODE_SV39X4 || >> + cap->args[0] > kvm_riscv_gstage_max_mode) >> + return -EINVAL; >> + if (kvm->arch.gstage_mode_initialized) >> + return 0; > >I think we want to return -EBUSY here and it should be documented where it >already states "...can only be set once per VM" Agreed. >> + kvm->arch.gstage_mode_initialized = true; > >In the previous patch I thought we were missing this, but I see now it >means "user initialized". Let's rename it as such, > > gstage_mode_user_initialized Agreed. >> + kvm->arch.kvm_riscv_gstage_mode = cap->args[0]; >> + kvm->arch.kvm_riscv_gstage_pgd_levels = 3 + >> + kvm->arch.kvm_riscv_gstage_mode - HGATP_MODE_SV39X4; >> + kvm_info("using SV%lluX4 G-stage page table format\n", >> + 39 + (cap->args[0] - HGATP_MODE_SV39X4) * 9); >> +#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 >> >> struct kvm_irq_routing_irqchip { >> __u32 irqchip; >> -- >> 2.50.1 >> > >Thanks, >drew > Thanks, Fangyu _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv