Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932862AbbFEGoC (ORCPT ); Fri, 5 Jun 2015 02:44:02 -0400 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:40177 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932415AbbFEGhI (ORCPT ); Fri, 5 Jun 2015 02:37:08 -0400 From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Cc: Alexey Kardashevskiy , Alex Williamson , Benjamin Herrenschmidt , David Gibson , Gavin Shan , Paul Mackerras , Wei Yang , linux-kernel@vger.kernel.org Subject: [PATCH kernel v12 09/34] vfio: powerpc/spapr: Move locked_vm accounting to helpers Date: Fri, 5 Jun 2015 16:35:01 +1000 Message-Id: <1433486126-23551-10-git-send-email-aik@ozlabs.ru> X-Mailer: git-send-email 2.4.0.rc3.8.gfb3e7d5 In-Reply-To: <1433486126-23551-1-git-send-email-aik@ozlabs.ru> References: <1433486126-23551-1-git-send-email-aik@ozlabs.ru> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15060506-0009-0000-0000-000001852A36 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5546 Lines: 166 There moves locked pages accounting to helpers. Later they will be reused for Dynamic DMA windows (DDW). This reworks debug messages to show the current value and the limit. This stores the locked pages number in the container so when unlocking the iommu table pointer won't be needed. This does not have an effect now but it will with the multiple tables per container as then we will allow attaching/detaching groups on fly and we may end up having a container with no group attached but with the counter incremented. While we are here, update the comment explaining why RLIMIT_MEMLOCK might be required to be bigger than the guest RAM. This also prints pid of the current process in pr_warn/pr_debug. Signed-off-by: Alexey Kardashevskiy [aw: for the vfio related changes] Acked-by: Alex Williamson Reviewed-by: David Gibson Reviewed-by: Gavin Shan --- Changes: v12: * added WARN_ON_ONCE() to decrement_locked_vm() for the sake of documentation v4: * new helpers do nothing if @npages == 0 * tce_iommu_disable() now can decrement the counter if the group was detached (not possible now but will be in the future) --- drivers/vfio/vfio_iommu_spapr_tce.c | 82 ++++++++++++++++++++++++++++--------- 1 file changed, 63 insertions(+), 19 deletions(-) diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c index 64300cc..6e2e15f 100644 --- a/drivers/vfio/vfio_iommu_spapr_tce.c +++ b/drivers/vfio/vfio_iommu_spapr_tce.c @@ -29,6 +29,51 @@ static void tce_iommu_detach_group(void *iommu_data, struct iommu_group *iommu_group); +static long try_increment_locked_vm(long npages) +{ + long ret = 0, locked, lock_limit; + + if (!current || !current->mm) + return -ESRCH; /* process exited */ + + if (!npages) + return 0; + + down_write(¤t->mm->mmap_sem); + locked = current->mm->locked_vm + npages; + lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; + if (locked > lock_limit && !capable(CAP_IPC_LOCK)) + ret = -ENOMEM; + else + current->mm->locked_vm += npages; + + pr_debug("[%d] RLIMIT_MEMLOCK +%ld %ld/%ld%s\n", current->pid, + npages << PAGE_SHIFT, + current->mm->locked_vm << PAGE_SHIFT, + rlimit(RLIMIT_MEMLOCK), + ret ? " - exceeded" : ""); + + up_write(¤t->mm->mmap_sem); + + return ret; +} + +static void decrement_locked_vm(long npages) +{ + if (!current || !current->mm || !npages) + return; /* process exited */ + + down_write(¤t->mm->mmap_sem); + if (WARN_ON_ONCE(npages > current->mm->locked_vm)) + npages = current->mm->locked_vm; + current->mm->locked_vm -= npages; + pr_debug("[%d] RLIMIT_MEMLOCK -%ld %ld/%ld\n", current->pid, + npages << PAGE_SHIFT, + current->mm->locked_vm << PAGE_SHIFT, + rlimit(RLIMIT_MEMLOCK)); + up_write(¤t->mm->mmap_sem); +} + /* * VFIO IOMMU fd for SPAPR_TCE IOMMU implementation * @@ -45,6 +90,7 @@ struct tce_container { struct mutex lock; struct iommu_table *tbl; bool enabled; + unsigned long locked_pages; }; static bool tce_page_is_contained(struct page *page, unsigned page_shift) @@ -60,7 +106,7 @@ static bool tce_page_is_contained(struct page *page, unsigned page_shift) static int tce_iommu_enable(struct tce_container *container) { int ret = 0; - unsigned long locked, lock_limit, npages; + unsigned long locked; struct iommu_table *tbl = container->tbl; if (!container->tbl) @@ -89,21 +135,22 @@ static int tce_iommu_enable(struct tce_container *container) * Also we don't have a nice way to fail on H_PUT_TCE due to ulimits, * that would effectively kill the guest at random points, much better * enforcing the limit based on the max that the guest can map. + * + * Unfortunately at the moment it counts whole tables, no matter how + * much memory the guest has. I.e. for 4GB guest and 4 IOMMU groups + * each with 2GB DMA window, 8GB will be counted here. The reason for + * this is that we cannot tell here the amount of RAM used by the guest + * as this information is only available from KVM and VFIO is + * KVM agnostic. */ - down_write(¤t->mm->mmap_sem); - npages = (tbl->it_size << tbl->it_page_shift) >> PAGE_SHIFT; - locked = current->mm->locked_vm + npages; - lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; - if (locked > lock_limit && !capable(CAP_IPC_LOCK)) { - pr_warn("RLIMIT_MEMLOCK (%ld) exceeded\n", - rlimit(RLIMIT_MEMLOCK)); - ret = -ENOMEM; - } else { + locked = (tbl->it_size << tbl->it_page_shift) >> PAGE_SHIFT; + ret = try_increment_locked_vm(locked); + if (ret) + return ret; - current->mm->locked_vm += npages; - container->enabled = true; - } - up_write(¤t->mm->mmap_sem); + container->locked_pages = locked; + + container->enabled = true; return ret; } @@ -115,13 +162,10 @@ static void tce_iommu_disable(struct tce_container *container) container->enabled = false; - if (!container->tbl || !current->mm) + if (!current->mm) return; - down_write(¤t->mm->mmap_sem); - current->mm->locked_vm -= (container->tbl->it_size << - container->tbl->it_page_shift) >> PAGE_SHIFT; - up_write(¤t->mm->mmap_sem); + decrement_locked_vm(container->locked_pages); } static void *tce_iommu_open(unsigned long arg) -- 2.4.0.rc3.8.gfb3e7d5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/