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Tsirkin" To: Sairaj Kodilkar Cc: Alejandro Jimenez , qemu-devel@nongnu.org, clement.mathieu--drif@eviden.com, pbonzini@redhat.com, richard.henderson@linaro.org, eduardo@habkost.net, peterx@redhat.com, david@redhat.com, philmd@linaro.org, marcel.apfelbaum@gmail.com, alex.williamson@redhat.com, imammedo@redhat.com, anisinha@redhat.com, vasant.hegde@amd.com, suravee.suthikulpanit@amd.com, santosh.shukla@amd.com, Wei.Huang2@amd.com, Ankit.Soni@amd.com, ethan.milon@eviden.com, joao.m.martins@oracle.com, boris.ostrovsky@oracle.com Subject: Re: [PATCH v3 18/22] amd_iommu: Toggle address translation mode on devtab entry invalidation Message-ID: <20251006021525-mutt-send-email-mst@kernel.org> References: <20250919213515.917111-1-alejandro.j.jimenez@oracle.com> <20250919213515.917111-19-alejandro.j.jimenez@oracle.com> <4856d645-ad17-4660-8012-3d315e56a463@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4856d645-ad17-4660-8012-3d315e56a463@amd.com> Received-SPF: pass client-ip=170.10.129.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.43, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Oct 06, 2025 at 11:38:28AM +0530, Sairaj Kodilkar wrote: > > > On 9/20/2025 3:05 AM, Alejandro Jimenez wrote: > > A guest must issue an INVALIDATE_DEVTAB_ENTRY command after changing a > > Device Table entry (DTE) e.g. after attaching a device and setting up its > > DTE. When intercepting this event, determine if the DTE has been configured > > for paging or not, and toggle the appropriate memory regions to allow DMA > > address translation for the address space if needed. Requires dma-remap=on. > > > > Signed-off-by: Alejandro Jimenez > > --- > > hw/i386/amd_iommu.c | 122 +++++++++++++++++++++++++++++++++++++++++++- > > 1 file changed, 120 insertions(+), 2 deletions(-) > > > > diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c > > index ce5d4c36624fd..e916dcb2be381 100644 > > --- a/hw/i386/amd_iommu.c > > +++ b/hw/i386/amd_iommu.c > > @@ -1032,18 +1032,136 @@ static void amdvi_reset_address_translation_all(AMDVIState *s) > > } > > } > > +static void enable_dma_mode(AMDVIAddressSpace *as, bool inval_current) > > +{ > > + /* > > + * When enabling DMA mode for the purpose of isolating guest devices on > > + * a failure to retrieve or invalid DTE, all existing mappings must be > > + * dropped. > > + */ > > + if (inval_current) { > > + IOMMUNotifier *n; > > + IOMMU_NOTIFIER_FOREACH(n, &as->iommu) { > > + amdvi_address_space_unmap(as, n); > > + } > > + } > > + > > + if (as->addr_translation) { > > + return; > > + } > > + > > + /* Installing DTE enabling translation, activate region */ > > + as->addr_translation = true; > > + amdvi_switch_address_space(as); > > + /* Sync shadow page tables */ > > + amdvi_address_space_sync(as); > Hi Alejandro, > I think we can skip amdvi_address_space_sync, because > amdvi_switch_address_space will trigger > amdvi_iommu_replay. this replay should unmap all the old mappings and sync > shadow page table. > > Thanks > Sairaj Well I queued this but this speedup can be done on top. -- MST