[xen staging] vtd: improve IOMMU TLB flush

[patchbot@xxxxxxx]

commit 5fe515a0fede07543f2a3b049167b1fd8b873caf
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Jul 7 14:37:46 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jul 7 14:37:46 2020 +0200

    vtd: improve IOMMU TLB flush
    
    Do not limit PSI flushes to order 0 pages, in order to avoid doing a
    full TLB flush if the passed in page has an order greater than 0 and
    is aligned. Should increase the performance of IOMMU TLB flushes when
    dealing with page orders greater than 0.
    
    This is part of XSA-321.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/drivers/passthrough/vtd/iommu.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 208b33c0e4..dcc9b7a35e 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -576,13 +576,14 @@ static int __must_check iommu_flush_iotlb(struct domain 
*d, dfn_t dfn,
         if ( iommu_domid == -1 )
             continue;
 
-        if ( page_count != 1 || dfn_eq(dfn, INVALID_DFN) )
+        if ( !page_count || (page_count & (page_count - 1)) ||
+             dfn_eq(dfn, INVALID_DFN) || !IS_ALIGNED(dfn_x(dfn), page_count) )
             rc = iommu_flush_iotlb_dsi(iommu, iommu_domid,
                                        0, flush_dev_iotlb);
         else
             rc = iommu_flush_iotlb_psi(iommu, iommu_domid,
                                        dfn_to_daddr(dfn),
-                                       PAGE_ORDER_4K,
+                                       get_order_from_pages(page_count),
                                        !dma_old_pte_present,
                                        flush_dev_iotlb);
 
--
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