From 146341187adf99cde71a8d63dbf4733d6a3932ca Mon Sep 17 00:00:00 2001 From: Ting-Wei Lan Date: Thu, 6 Aug 2015 01:10:06 +0800 Subject: [PATCH] VT-d: add iommu=igfx option to workaround graphics issues When using Linux >= 3.19 (commit 47591df) as dom0 on some Intel Ironlake devices, It is possible to encounter graphics issues that make screen unreadable or crash the system. It was reported in freedesktop bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90037 As we still cannot find a proper fix for this problem, this patch adds iommu=igfx option to control whether Intel graphics IOMMU is enabled. Running Xen with iommu=no-igfx is similar to running Linux with intel_iommu=igfx_off, which disables IOMMU for Intel GPU. This can be used by users to manually workaround the problem before a fix is available for i915 driver. Signed-off-by: Ting-Wei Lan Reviewed-by: Andrew Cooper Release-acked-by: Wei Liu Acked-by: Kevin Tian --- docs/misc/xen-command-line.markdown | 11 ++++++++++- xen/drivers/passthrough/iommu.c | 3 +++ xen/drivers/passthrough/vtd/quirks.c | 3 +++ xen/include/xen/iommu.h | 2 +- 4 files changed, 17 insertions(+), 2 deletions(-) diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown index 204e7a4f46..a2e427cb18 100644 --- a/docs/misc/xen-command-line.markdown +++ b/docs/misc/xen-command-line.markdown @@ -855,7 +855,7 @@ debug hypervisor only). > Default: `new` unless directed-EOI is supported ### iommu -> `= List of [ | force | required | intremap | qinval | snoop | sharept | dom0-passthrough | dom0-strict | amd-iommu-perdev-intremap | workaround_bios_bug | verbose | debug ]` +> `= List of [ | force | required | intremap | qinval | snoop | sharept | dom0-passthrough | dom0-strict | amd-iommu-perdev-intremap | workaround_bios_bug | igfx | verbose | debug ]` > Sub-options: @@ -929,6 +929,15 @@ debug hypervisor only). >> ignored (normally IOMMU setup fails if any of the devices listed by a DRHD >> entry aren't PCI discoverable). +> `igfx` (VT-d) + +> Default: `true` + +>> Enable IOMMU for Intel graphics devices. The intended usage of this option +>> is `no-igfx`, which is similar to Linux `intel_iommu=igfx_off` option used +>> to workaround graphics issues. If adding `no-igfx` fixes anything, you +>> should file a bug reporting the problem. + > `verbose` > Default: `false` diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c index 11d58cc82a..fc7831e70a 100644 --- a/xen/drivers/passthrough/iommu.c +++ b/xen/drivers/passthrough/iommu.c @@ -46,6 +46,7 @@ bool_t __read_mostly force_iommu; bool_t __hwdom_initdata iommu_dom0_strict; bool_t __read_mostly iommu_verbose; bool_t __read_mostly iommu_workaround_bios_bug; +bool_t __read_mostly iommu_igfx = 1; bool_t __read_mostly iommu_passthrough; bool_t __read_mostly iommu_snoop = 1; bool_t __read_mostly iommu_qinval = 1; @@ -86,6 +87,8 @@ static void __init parse_iommu_param(char *s) force_iommu = val; else if ( !strcmp(s, "workaround_bios_bug") ) iommu_workaround_bios_bug = val; + else if ( !strcmp(s, "igfx") ) + iommu_igfx = val; else if ( !strcmp(s, "verbose") ) iommu_verbose = val; else if ( !strcmp(s, "snoop") ) diff --git a/xen/drivers/passthrough/vtd/quirks.c b/xen/drivers/passthrough/vtd/quirks.c index 921e166109..1888843dff 100644 --- a/xen/drivers/passthrough/vtd/quirks.c +++ b/xen/drivers/passthrough/vtd/quirks.c @@ -71,6 +71,9 @@ int is_igd_vt_enabled_quirk(void) { u16 ggc; + if ( !iommu_igfx ) + return 0; + if ( !IS_ILK(ioh_id) ) return 1; diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h index 705969b552..8f3a20eb32 100644 --- a/xen/include/xen/iommu.h +++ b/xen/include/xen/iommu.h @@ -29,7 +29,7 @@ extern bool_t iommu_enable, iommu_enabled; extern bool_t force_iommu, iommu_verbose; -extern bool_t iommu_workaround_bios_bug, iommu_passthrough; +extern bool_t iommu_workaround_bios_bug, iommu_igfx, iommu_passthrough; extern bool_t iommu_snoop, iommu_qinval, iommu_intremap; extern bool_t iommu_hap_pt_share; extern bool_t iommu_debug; -- 2.39.5