From 2e1c8dafb8c2c459baa5aef5b338c15edd9b9b5b Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Tue, 12 Jul 2022 08:08:55 +0800 Subject: [PATCH] iommu/vt-d: Unnecessary spinlock for root table alloc and free The IOMMU root table is allocated and freed in the IOMMU initialization code in static boot or hot-remove paths. There's no need for a spinlock. Signed-off-by: Lu Baolu Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/20220706025524.2904370-5-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/iommu/intel/iommu.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 77915d61f7ec..ff49c9460ede 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -809,14 +809,12 @@ static int device_context_mapped(struct intel_iommu *iommu, u8 bus, u8 devfn) static void free_context_table(struct intel_iommu *iommu) { - int i; - unsigned long flags; struct context_entry *context; + int i; + + if (!iommu->root_entry) + return; - spin_lock_irqsave(&iommu->lock, flags); - if (!iommu->root_entry) { - goto out; - } for (i = 0; i < ROOT_ENTRY_NR; i++) { context = iommu_context_addr(iommu, i, 0, 0); if (context) @@ -828,12 +826,10 @@ static void free_context_table(struct intel_iommu *iommu) context = iommu_context_addr(iommu, i, 0x80, 0); if (context) free_pgtable_page(context); - } + free_pgtable_page(iommu->root_entry); iommu->root_entry = NULL; -out: - spin_unlock_irqrestore(&iommu->lock, flags); } #ifdef CONFIG_DMAR_DEBUG @@ -1232,7 +1228,6 @@ static void domain_unmap(struct dmar_domain *domain, unsigned long start_pfn, static int iommu_alloc_root_entry(struct intel_iommu *iommu) { struct root_entry *root; - unsigned long flags; root = (struct root_entry *)alloc_pgtable_page(iommu->node); if (!root) { @@ -1242,10 +1237,7 @@ static int iommu_alloc_root_entry(struct intel_iommu *iommu) } __iommu_flush_cache(iommu, root, ROOT_SIZE); - - spin_lock_irqsave(&iommu->lock, flags); iommu->root_entry = root; - spin_unlock_irqrestore(&iommu->lock, flags); return 0; }