From: Chao Gao Date: Thu, 13 Apr 2017 15:34:29 +0000 (+0200) Subject: VT-d: correct a comment and remove an useless if() statement X-Git-Tag: 4.9.0-rc2~13 X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=dc0e69aa41e47c1d23ca6ed939272aa11c476f12;p=xen.git VT-d: correct a comment and remove an useless if() statement Fix two flaws in the patch (93358e8e VT-d: introduce update_irte to update irte safely): 1. Expand a comment in update_irte() to make it clear that VT-d hardware doesn't update IRTE and software can't update IRTE behind us since we hold iremap_lock. 2. remove an useless if() statement Signed-off-by: Chao Gao Reviewed-by: Jan Beulich Acked-by: Kevin Tian Release-acked-by: Julien Grall --- diff --git a/xen/drivers/passthrough/vtd/intremap.c b/xen/drivers/passthrough/vtd/intremap.c index 699239b006..1e0317c47a 100644 --- a/xen/drivers/passthrough/vtd/intremap.c +++ b/xen/drivers/passthrough/vtd/intremap.c @@ -200,8 +200,10 @@ static void update_irte(struct iommu *iommu, struct iremap_entry *entry, else { /* - * If the caller requests an atomic update but we can't meet it, - * a bug will be raised. + * VT-d hardware doesn't update IRTEs behind us, nor the software + * since we hold iremap_lock. If the caller wants VT-d hardware to + * always see a consistent entry, but we can't meet it, a bug will + * be raised. */ if ( entry->lo == new_ire->lo ) write_atomic(&entry->hi, new_ire->hi); @@ -690,8 +692,7 @@ static int msi_msg_to_remap_entry( remap_rte->data = index - i; update_irte(iommu, iremap_entry, &new_ire, msi_desc->irte_initialized); - if ( !msi_desc->irte_initialized ) - msi_desc->irte_initialized = true; + msi_desc->irte_initialized = true; iommu_flush_cache_entry(iremap_entry, sizeof(*iremap_entry)); iommu_flush_iec_index(iommu, 0, index);