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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 C081ACA5FA0 for ; Tue, 20 Jan 2026 16:11:36 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 55F7110E626; Tue, 20 Jan 2026 16:11:36 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="WH9FE9yU"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.19]) by gabe.freedesktop.org (Postfix) with ESMTPS id 86EC210E626 for ; Tue, 20 Jan 2026 16:11:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1768925495; x=1800461495; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=wItH6JYEUrIaQ9/hhcz+aBkOKBsbuMrGwki6nH5xNhY=; b=WH9FE9yU06RFNamkQ03wTvMnrptLK/q6+KUDEQiYRynKoPAVWpcVzGcp uGsfvJBTAm3Rzmg1TUhcgOB6chEiU9t+1RJX5qt/nGvSY4lMxCchPcW6j nb2RYAPyh2O8dLtw9b3l46CL7B9XnfC4PsK/p6P1V5MHuz95T79Oj4cMz FUILCpc5mH2RwzaMjS4kpDcl9uAMmM09aFgGu7/WQR/LUvXC/s0Quhs6B 1gLHYm9G2PLE7xWaGIrT942cNjcjpJCBTYVQSsr/2hWA/JpmC1pgiAMd9 DcECAkQ+wErOtSMSlRUslbzBMlHaG5mkF7fgAeJi2EK3zIGFocQ6ZOE7g g==; X-CSE-ConnectionGUID: /8xzVf8hQe2mjcEh00uITw== X-CSE-MsgGUID: IfWLmZQGQC2jWIrgDdG/Uw== X-IronPort-AV: E=McAfee;i="6800,10657,11677"; a="70042872" X-IronPort-AV: E=Sophos;i="6.21,240,1763452800"; d="scan'208";a="70042872" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jan 2026 08:11:35 -0800 X-CSE-ConnectionGUID: dPJD5DX4RQ+p0TvdjLB/ig== X-CSE-MsgGUID: TfVVNKOPQ+OGan7RNN+kgw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,240,1763452800"; d="scan'208";a="206199455" Received: from smoticic-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.245.13]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jan 2026 08:11:32 -0800 Date: Tue, 20 Jan 2026 18:11:28 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Jia Yao Cc: intel-gfx@lists.freedesktop.org, Alex Zuo , Shuicheng Lin , Askar Safin , Pingfan Liu , Chris Wilson Subject: Re: [PATCH v3] drm/i915: Clearing the Memory Space Enable bit when disabling i915 Message-ID: References: <20251007180634.912006-1-jia.yao@intel.com> <20260120044203.2436044-1-jia.yao@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260120044203.2436044-1-jia.yao@intel.com> X-Patchwork-Hint: comment Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs Bertel Jungin Aukio 5, 02600 Espoo, Finland X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Tue, Jan 20, 2026 at 04:42:03AM +0000, Jia Yao wrote: > In a kexec reboot scenario, the GPU's Global Graphics Translation Table > (GGTT) retains its previous state after the kernel is reloaded, until i915 > reinitializes the GGTT. > > The simple-framebuffer driver is initialized before i915 and accesses the > PCIe memory space (GPU aperture) through outdated GGTT entries. This leads > to invalid physical memory accesses, causing GPF or data corruption. > > To prevent such issues, the Memory Space Enable (MSE) bit in the PCI Command > Register is cleared during i915_driver_shutdown. This disables all PCIe > memory space access (including MMIO and aperture) at the hardware level. > After the kernel is reloaded, access to the PCIe memory space will be > forbidden until i915 is re-initialized. Still looks like a hack. I think the correct fix would involve preventing the kexec'd kernel from initializing the fb driver that is doing the invalid memory accesses. > > Since disabling PCIe memory space affects all MMIO operations, PXP shutdown > needs to be completed before this point. Calls intel_pxp_fini() before > disabling memory space to ensure PXP cleanup can still access MMIO registers. > > v2: > - follow brace style > > v3: > - revise description > > Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14598 > Cc: Alex Zuo > Cc: Shuicheng Lin > Cc: Askar Safin > Cc: Pingfan Liu > Suggested-by: Chris Wilson > Signed-off-by: Jia Yao > --- > drivers/gpu/drm/i915/i915_driver.c | 35 +++++++++++++++++++++++++++--- > 1 file changed, 32 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c > index b46cb54ef5dc..766f85726b67 100644 > --- a/drivers/gpu/drm/i915/i915_driver.c > +++ b/drivers/gpu/drm/i915/i915_driver.c > @@ -118,6 +118,33 @@ > > static const struct drm_driver i915_drm_driver; > > +static int i915_enable_device(struct pci_dev *pdev) > +{ > + u32 cmd; > + int ret; > + > + ret = pci_enable_device(pdev); > + if (ret) > + return ret; > + > + pci_read_config_dword(pdev, PCI_COMMAND, &cmd); > + if (!(cmd & PCI_COMMAND_MEMORY)) > + pci_write_config_dword(pdev, PCI_COMMAND, cmd | PCI_COMMAND_MEMORY); > + > + return 0; > +} > + > +static void i915_disable_device(struct pci_dev *pdev) > +{ > + u32 cmd; > + > + pci_read_config_dword(pdev, PCI_COMMAND, &cmd); > + if (cmd & PCI_COMMAND_MEMORY) > + pci_write_config_dword(pdev, PCI_COMMAND, cmd & ~PCI_COMMAND_MEMORY); > + > + pci_disable_device(pdev); > +} > + > static int i915_workqueues_init(struct drm_i915_private *dev_priv) > { > /* > @@ -788,7 +815,7 @@ int i915_driver_probe(struct pci_dev *pdev, const struct pci_device_id *ent) > struct intel_display *display; > int ret; > > - ret = pci_enable_device(pdev); > + ret = i915_enable_device(pdev); > if (ret) { > pr_err("Failed to enable graphics device: %pe\n", ERR_PTR(ret)); > return ret; > @@ -796,7 +823,7 @@ int i915_driver_probe(struct pci_dev *pdev, const struct pci_device_id *ent) > > i915 = i915_driver_create(pdev, ent); > if (IS_ERR(i915)) { > - pci_disable_device(pdev); > + i915_disable_device(pdev); > return PTR_ERR(i915); > } > > @@ -885,7 +912,7 @@ int i915_driver_probe(struct pci_dev *pdev, const struct pci_device_id *ent) > enable_rpm_wakeref_asserts(&i915->runtime_pm); > i915_driver_late_release(i915); > out_pci_disable: > - pci_disable_device(pdev); > + i915_disable_device(pdev); > i915_probe_error(i915, "Device initialization failed (%d)\n", ret); > return ret; > } > @@ -1003,6 +1030,7 @@ void i915_driver_shutdown(struct drm_i915_private *i915) > > intel_dmc_suspend(display); > > + intel_pxp_fini(i915); > i915_gem_suspend(i915); > > /* > @@ -1020,6 +1048,7 @@ void i915_driver_shutdown(struct drm_i915_private *i915) > enable_rpm_wakeref_asserts(&i915->runtime_pm); > > intel_runtime_pm_driver_last_release(&i915->runtime_pm); > + i915_disable_device(to_pci_dev(i915->drm.dev)); > } > > static bool suspend_to_idle(struct drm_i915_private *dev_priv) > -- > 2.34.1 -- Ville Syrjälä Intel