From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20120607040340.344605807@linuxfoundation.org> Date: Thu, 07 Jun 2012 13:04:03 +0900 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Joerg Roedel Subject: [ 27/82] iommu/amd: Add workaround for event log erratum In-Reply-To: <20120607041406.GA13233@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Joerg Roedel commit 3d06fca8d2aa3543030e40b95f1d62f9f5a03540 upstream. Due to a recent erratum it can happen that the head pointer of the event-log is updated before the actual event-log entry is written. This patch implements the recommended workaround. Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman --- drivers/iommu/amd_iommu.c | 29 +++++++++++++++++++++++------ 1 file changed, 23 insertions(+), 6 deletions(-) --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -450,12 +450,27 @@ static void dump_command(unsigned long p static void iommu_print_event(struct amd_iommu *iommu, void *__evt) { - u32 *event = __evt; - int type = (event[1] >> EVENT_TYPE_SHIFT) & EVENT_TYPE_MASK; - int devid = (event[0] >> EVENT_DEVID_SHIFT) & EVENT_DEVID_MASK; - int domid = (event[1] >> EVENT_DOMID_SHIFT) & EVENT_DOMID_MASK; - int flags = (event[1] >> EVENT_FLAGS_SHIFT) & EVENT_FLAGS_MASK; - u64 address = (u64)(((u64)event[3]) << 32) | event[2]; + int type, devid, domid, flags; + volatile u32 *event = __evt; + int count = 0; + u64 address; + +retry: + type = (event[1] >> EVENT_TYPE_SHIFT) & EVENT_TYPE_MASK; + devid = (event[0] >> EVENT_DEVID_SHIFT) & EVENT_DEVID_MASK; + domid = (event[1] >> EVENT_DOMID_SHIFT) & EVENT_DOMID_MASK; + flags = (event[1] >> EVENT_FLAGS_SHIFT) & EVENT_FLAGS_MASK; + address = (u64)(((u64)event[3]) << 32) | event[2]; + + if (type == 0) { + /* Did we hit the erratum? */ + if (++count == LOOP_TIMEOUT) { + pr_err("AMD-Vi: No event written to event log\n"); + return; + } + udelay(1); + goto retry; + } printk(KERN_ERR "AMD-Vi: Event logged ["); @@ -508,6 +523,8 @@ static void iommu_print_event(struct amd default: printk(KERN_ERR "UNKNOWN type=0x%02x]\n", type); } + + memset(__evt, 0, 4 * sizeof(u32)); } static void iommu_poll_events(struct amd_iommu *iommu)