From mboxrd@z Thu Jan 1 00:00:00 1970 From: Quan Xu Subject: [PATCH] vt-d: Fix IM bit unmask of Fault Event Control Register in init_vtd_hw(). Date: Fri, 25 Sep 2015 15:22:35 +0800 Message-ID: <1443165755-89680-1-git-send-email-quan.xu@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: yang.z.zhang@intel.com, kevin.tian@intel.com, xen-devel@lists.xen.org Cc: Quan Xu , jbeulich@suse.com List-Id: xen-devel@lists.xenproject.org Bit 0:29 in Fault Event Control Register are 'Reserved and Preserved', software cannot write 0 to it unconditionally. Software must preserve the value read for writes. Signed-off-by: Quan Xu Reported-by: Jan Beulich --- xen/drivers/passthrough/vtd/iommu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/xen/drivers/passthrough/vtd/iommu.c b/xen/drivers/passthrough/vtd/iommu.c index f31d41b..bf9d6e8 100644 --- a/xen/drivers/passthrough/vtd/iommu.c +++ b/xen/drivers/passthrough/vtd/iommu.c @@ -2277,6 +2277,7 @@ static int init_vtd_hw(void) struct iommu_flush *flush = NULL; int ret; unsigned long flags; + u32 sts; /* * Basic VT-d HW init: set VT-d interrupt, clear VT-d faults. @@ -2290,7 +2291,9 @@ static int init_vtd_hw(void) clear_fault_bits(iommu); spin_lock_irqsave(&iommu->register_lock, flags); - dmar_writel(iommu->reg, DMAR_FECTL_REG, 0); + sts = dmar_readl(iommu->reg, DMAR_FECTL_REG); + sts &= ~DMA_FECTL_IM; + dmar_writel(iommu->reg, DMAR_FECTL_REG, sts); spin_unlock_irqrestore(&iommu->register_lock, flags); } -- 1.8.3.2