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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1726569174; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HE4LPiIytCKu+JhxwChIGIhq1x6MX/XG0Gp6icN+mLY=; b=erfBVMXKmHoEJDVt6rWFNdlCaa2I+tHM2TcyZDmfeZGSQI7gd2mkoeCMN0kv2fsp+H96/d +NI1/n1/f1GnfkZKaXDpg8h9ryCXG2KFwwJD2r2AKFQ1PXTzGuOX7suG9iOZJAJ8jnIHZc cbcTFOjFAGaqHOBT/G1eJyZbvcUCTTA= X-MC-Unique: YgwbVuPPO1yMbN49vohlEg-1 From: =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= To: qemu-devel@nongnu.org Cc: Alex Williamson , =?UTF-8?q?Corvin=20K=C3=B6hne?= , =?UTF-8?q?Corvin=20K=C3=B6hne?= Subject: [PULL 7/8] vfio/igd: don't set stolen memory size to zero Date: Tue, 17 Sep 2024 12:32:28 +0200 Message-ID: <20240917103229.876515-8-clg@redhat.com> In-Reply-To: <20240917103229.876515-1-clg@redhat.com> References: <20240917103229.876515-1-clg@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=clg@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1726569244286116600 From: Corvin K=C3=B6hne The stolen memory is required for the GOP (EFI) driver and the Windows driver. While the GOP driver seems to work with any stolen memory size, the Windows driver will crash if the size doesn't match the size allocated by the host BIOS. For that reason, it doesn't make sense to overwrite the stolen memory size. It's true that this wastes some VM memory. In the worst case, the stolen memory can take up more than a GB. However, that's uncommon. Additionally, it's likely that a bunch of RAM is assigned to VMs making use of GPU passthrough. Signed-off-by: Corvin K=C3=B6hne Reviewed-by: Alex Williamson --- hw/vfio/igd.c | 35 ++++++++++++++++++----------------- 1 file changed, 18 insertions(+), 17 deletions(-) diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c index 8a41b16421b425688dd2cacd3a113efbad82e91b..0751c43eae04aac5152c627af64= 8319151ee1e39 100644 --- a/hw/vfio/igd.c +++ b/hw/vfio/igd.c @@ -478,6 +478,23 @@ void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, in= t nr) QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, quirk, next); } =20 +static int igd_get_stolen_mb(int gen, uint32_t gmch) +{ + int gms; + + if (gen < 8) { + gms =3D (gmch >> 3) & 0x1f; + } else { + gms =3D (gmch >> 8) & 0xff; + } + + if (gms > 0x10) { + error_report("Unsupported IGD GMS value 0x%x", gms); + return 0; + } + return gms * 32; +} + void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr) { g_autofree struct vfio_region_info *rom =3D NULL; @@ -655,23 +672,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, in= t nr) ggms_mb =3D 1 << ggms_mb; } =20 - /* - * Assume we have no GMS memory, but allow it to be overridden by devi= ce - * option (experimental). The spec doesn't actually allow zero GMS wh= en - * when IVD (IGD VGA Disable) is clear, but the claim is that it's unu= sed, - * so let's not waste VM memory for it. - */ - gmch &=3D ~((gen < 8 ? 0x1f : 0xff) << (gen < 8 ? 3 : 8)); - - if (vdev->igd_gms) { - if (vdev->igd_gms <=3D 0x10) { - gms_mb =3D vdev->igd_gms * 32; - gmch |=3D vdev->igd_gms << (gen < 8 ? 3 : 8); - } else { - error_report("Unsupported IGD GMS value 0x%x", vdev->igd_gms); - vdev->igd_gms =3D 0; - } - } + gms_mb =3D igd_get_stolen_mb(gen, gmch); =20 /* * Request reserved memory for stolen memory via fw_cfg. VM firmware --=20 2.46.0