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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8f7c4dbcfbdsm203538685a.12.2026.04.28.06.38.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Apr 2026 06:38:01 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wHidU-0000000Aj1L-1JSZ; Tue, 28 Apr 2026 10:38:00 -0300 Date: Tue, 28 Apr 2026 10:38:00 -0300 From: Jason Gunthorpe To: fangyu.yu@linux.alibaba.com Cc: joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, tjeznach@rivosinc.com, kevin.tian@intel.com, baolu.lu@linux.intel.com, vasant.hegde@amd.com, anup@brainfault.org, atish.patra@linux.dev, skhawaja@google.com, guoren@kernel.org, kvm@vger.kernel.org, iommu@lists.linux.dev, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 08/11] iommu/riscv: Add dirty tracking support for second-stage domains Message-ID: <20260428133800.GG849557@ziepe.ca> References: <20260428131359.34872-1-fangyu.yu@linux.alibaba.com> <20260428131359.34872-9-fangyu.yu@linux.alibaba.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260428131359.34872-9-fangyu.yu@linux.alibaba.com> On Tue, Apr 28, 2026 at 09:13:56PM +0800, fangyu.yu@linux.alibaba.com wrote: > @@ -1247,6 +1247,84 @@ static int riscv_iommu_attach_paging_domain(struct iommu_domain *iommu_domain, > return 0; > } > > +/* > + * Enable or disable hardware A/D bit updates (GADE) in the device context for > + * all devices attached to a second-stage domain. When dirty tracking is > + * enabled the IOMMU hardware will set the dirty bit in PTEs on write access, > + * making them visible to read_and_clear_dirty(). > + */ > +static int riscv_iommu_set_dirty_tracking(struct iommu_domain *iommu_domain, > + bool enable) > +{ > + struct riscv_iommu_domain *domain = iommu_domain_to_riscv(iommu_domain); > + struct riscv_iommu_bond *bond; > + struct riscv_iommu_device *iommu, *prev; > + struct riscv_iommu_dc *dc; > + struct iommu_fwspec *fwspec; > + struct riscv_iommu_command cmd; > + u64 tc; > + int i; > + > + rcu_read_lock(); > + > + list_for_each_entry_rcu(bond, &domain->bonds, list) { > + iommu = dev_to_iommu(bond->dev); > + fwspec = dev_iommu_fwspec_get(bond->dev); > + > + for (i = 0; i < fwspec->num_ids; i++) { > + dc = riscv_iommu_get_dc(iommu, fwspec->ids[i]); > + tc = READ_ONCE(dc->tc); > + if (!(tc & RISCV_IOMMU_DC_TC_V)) > + continue; > + > + if (enable) > + tc |= RISCV_IOMMU_DC_TC_GADE; > + else > + tc &= ~RISCV_IOMMU_DC_TC_GADE; > + WRITE_ONCE(dc->tc, tc); I'm pretty sure you don't need to do this. Just preset GADE when ever a S2 domain is attached, rely on the pre-set D to avoid any HW cost and you are fine. No need to change it dynamically unless something is reall weird about riscv. Jason