From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexey Kardashevskiy Subject: [PATCH kernel v11 19/34] powerpc/iommu: Fix IOMMU ownership control functions Date: Fri, 29 May 2015 18:44:43 +1000 Message-ID: <1432889098-22924-20-git-send-email-aik@ozlabs.ru> References: <1432889098-22924-1-git-send-email-aik@ozlabs.ru> Cc: Alexey Kardashevskiy , Alex Williamson , Benjamin Herrenschmidt , David Gibson , Gavin Shan , Paul Mackerras , kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: linuxppc-dev@lists.ozlabs.org Return-path: Received: from e23smtp05.au.ibm.com ([202.81.31.147]:51078 "EHLO e23smtp05.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755548AbbE2Iq1 (ORCPT ); Fri, 29 May 2015 04:46:27 -0400 Received: from /spool/local by e23smtp05.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 29 May 2015 18:46:25 +1000 In-Reply-To: <1432889098-22924-1-git-send-email-aik@ozlabs.ru> Sender: kvm-owner@vger.kernel.org List-ID: This adds missing locks in iommu_take_ownership()/ iommu_release_ownership(). This marks all pages busy in iommu_table::it_map in order to catch errors if there is an attempt to use this table while ownership over it is taken. This only clears TCE content if there is no page marked busy in it_map. Clearing must be done outside of the table locks as iommu_clear_tce() called from iommu_clear_tces_and_put_pages() does this. In order to use bitmap_empty(), the existing code clears bit#0 which is set even in an empty table if it is bus-mapped at 0 as iommu_init_table() reserves page#0 to prevent buggy drivers from crashing when allocated page is bus-mapped at zero (which is correct). This restores the bit in the case of failure to bring the it_map to the state it was in when we called iommu_take_ownership(). Signed-off-by: Alexey Kardashevskiy Reviewed-by: David Gibson Reviewed-by: Gavin Shan --- Changes: v9: * iommu_table_take_ownership() did not return @ret (and ignored EBUSY), now it does return correct error. * updated commit log about setting bit#0 in the case of failure v5: * do not store bit#0 value, it has to be set for zero-based table anyway * removed test_and_clear_bit --- arch/powerpc/kernel/iommu.c | 30 +++++++++++++++++++++++++----- 1 file changed, 25 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index b6a397a..1ae1034 100644 --- a/arch/powerpc/kernel/iommu.c +++ b/arch/powerpc/kernel/iommu.c @@ -1035,31 +1035,51 @@ EXPORT_SYMBOL_GPL(iommu_tce_build); int iommu_take_ownership(struct iommu_table *tbl) { - unsigned long sz = (tbl->it_size + 7) >> 3; + unsigned long flags, i, sz = (tbl->it_size + 7) >> 3; + int ret = 0; + + spin_lock_irqsave(&tbl->large_pool.lock, flags); + for (i = 0; i < tbl->nr_pools; i++) + spin_lock(&tbl->pools[i].lock); if (tbl->it_offset == 0) clear_bit(0, tbl->it_map); if (!bitmap_empty(tbl->it_map, tbl->it_size)) { pr_err("iommu_tce: it_map is not empty"); - return -EBUSY; + ret = -EBUSY; + /* Restore bit#0 set by iommu_init_table() */ + if (tbl->it_offset == 0) + set_bit(0, tbl->it_map); + } else { + memset(tbl->it_map, 0xff, sz); } - memset(tbl->it_map, 0xff, sz); + for (i = 0; i < tbl->nr_pools; i++) + spin_unlock(&tbl->pools[i].lock); + spin_unlock_irqrestore(&tbl->large_pool.lock, flags); - return 0; + return ret; } EXPORT_SYMBOL_GPL(iommu_take_ownership); void iommu_release_ownership(struct iommu_table *tbl) { - unsigned long sz = (tbl->it_size + 7) >> 3; + unsigned long flags, i, sz = (tbl->it_size + 7) >> 3; + + spin_lock_irqsave(&tbl->large_pool.lock, flags); + for (i = 0; i < tbl->nr_pools; i++) + spin_lock(&tbl->pools[i].lock); memset(tbl->it_map, 0, sz); /* Restore bit#0 set by iommu_init_table() */ if (tbl->it_offset == 0) set_bit(0, tbl->it_map); + + for (i = 0; i < tbl->nr_pools; i++) + spin_unlock(&tbl->pools[i].lock); + spin_unlock_irqrestore(&tbl->large_pool.lock, flags); } EXPORT_SYMBOL_GPL(iommu_release_ownership); -- 2.4.0.rc3.8.gfb3e7d5