Commit 2e1c8daf authored by Lu Baolu's avatar Lu Baolu Committed by Joerg Roedel
Browse files

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: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220706025524.2904370-5-baolu.lu@linux.intel.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 8ac0b64b

drivers/iommu/intel/iommu.c

+5 −13
Original line number Diff line number Diff line
@@ -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;

}