Re: [Xen-devel] [BUG] After upgrade to Xen 4.12.0 iommu=no-igfx

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Jul 25, 2019 at 05:47:19PM -0700, Roman Shaposhnik wrote:
> Hi Roger!
> 
> With your patch (and build as a debug build) Xen crashes on boot
> (which I guess was the point of your BUG_ON statement).

Yes, that's very weird, seems like entries are not added to the iommu
page tables but I have no idea why, AFAICT this works fine on my
system.

Do you have any patches on top of RELEASE-4.12.0?

I have another patch with more verbose output, could you give it a
try? It's maybe going to be more chatty than the previous one.

I'm sorry to keep you testing stuff, but since I cannot reproduce this
locally I have to rely on you to provide the debug output.

Thanks, Roger.
---8<---
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index b9bbb8f485..75f8359a99 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1331,7 +1331,7 @@ int set_identity_p2m_entry(struct domain *d, unsigned 
long gfn_l,
 
     if ( !paging_mode_translate(p2m->domain) )
     {
-        if ( !need_iommu_pt_sync(d) )
+        if ( !has_iommu_pt(d) )
             return 0;
         return iommu_legacy_map(d, _dfn(gfn_l), _mfn(gfn_l), PAGE_ORDER_4K,
                                 IOMMUF_readable | IOMMUF_writable);
@@ -1422,7 +1422,7 @@ int clear_identity_p2m_entry(struct domain *d, unsigned 
long gfn_l)
 
     if ( !paging_mode_translate(d) )
     {
-        if ( !need_iommu_pt_sync(d) )
+        if ( !has_iommu_pt(d) )
             return 0;
         return iommu_legacy_unmap(d, _dfn(gfn_l), PAGE_ORDER_4K);
     }
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 117b869b0c..214c5d515f 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -291,8 +291,18 @@ int iommu_map(struct domain *d, dfn_t dfn, mfn_t mfn,
     unsigned long i;
     int rc = 0;
 
+if (dfn_x(dfn) >= 0x8d800 && dfn_x(dfn) < 0x90000 )
+{
+    printk("<RMRR> iommu_map %#lx\n", dfn_x(dfn));
+    process_pending_softirqs();
+}
+
     if ( !iommu_enabled || !hd->platform_ops )
+{
+    printk("iommu_enabled: %d platform_ops %p\n",
+           iommu_enabled, hd->platform_ops);
         return 0;
+}
 
     ASSERT(IS_ALIGNED(dfn_x(dfn), (1ul << page_order)));
     ASSERT(IS_ALIGNED(mfn_x(mfn), (1ul << page_order)));
diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 50a0e25224..8c3fcb50ae 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -2009,12 +2009,33 @@ static int rmrr_identity_mapping(struct domain *d, 
bool_t map,
     if ( !map )
         return -ENOENT;
 
+printk("<RMRR> mapping %#lx - %#lx\n", base_pfn, end_pfn);
     while ( base_pfn < end_pfn )
     {
         int err = set_identity_p2m_entry(d, base_pfn, p2m_access_rw, flag);
+        mfn_t mfn;
+        unsigned int f;
 
         if ( err )
             return err;
+
+err = intel_iommu_lookup_page(d, _dfn(base_pfn), &mfn, &f);
+if ( err )
+{
+    printk("intel_iommu_lookup_page err: %d\n", err);
+    BUG();
+}
+if ( base_pfn != mfn_x(mfn) )
+{
+    printk("base_pfn: %#lx mfn: %#lx\n", base_pfn, mfn_x(mfn));
+    BUG();
+}
+if ( f != (IOMMUF_readable | IOMMUF_writable) )
+{
+    printk("flags: %#x\n", f);
+    BUG();
+}
+
         base_pfn++;
     }
 
@@ -2263,6 +2284,7 @@ static void __hwdom_init setup_hwdom_rmrr(struct domain 
*d)
     u16 bdf;
     int ret, i;
 
+printk("<RMRR> setting up regions\n");
     pcidevs_lock();
     for_each_rmrr_device ( rmrr, bdf, i )
     {

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