[Xen-changelog] [xen staging] vpci/msix: carve p2m hole for MSIX MMIO regions

[patchbot@xxxxxxx]

commit 677053fac17ab6f77510b1fa19056846b9029b69
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Mon Nov 26 15:41:42 2018 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Nov 26 15:41:42 2018 +0100

    vpci/msix: carve p2m hole for MSIX MMIO regions
    
    Make sure the MSIX MMIO regions don't have p2m entries setup, so that
    accesses to them trap into the hypervisor and can be handled by vpci.
    
    Commit 042678762 ("x86/iommu: add map-reserved dom0-iommu option to
    map reserved memory ranges") added mappings for all the reserved
    regions into the PVH Dom0 p2m, and some of those reserved regions
    might contain MSIX MMIO regions, hence the need to make sure there are
    no mappings established.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/drivers/vpci/header.c | 11 +++++++++++
 xen/drivers/vpci/msix.c   | 49 +++++++++++++++++++++++++++++++++++++++++++++++
 xen/include/xen/vpci.h    |  3 +++
 3 files changed, 63 insertions(+)

diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
index 92c00b68aa..43cac3f7d3 100644
--- a/xen/drivers/vpci/header.c
+++ b/xen/drivers/vpci/header.c
@@ -89,6 +89,17 @@ static void modify_decoding(const struct pci_dev *pdev, 
uint16_t cmd,
     bool map = cmd & PCI_COMMAND_MEMORY;
     unsigned int i;
 
+    /*
+     * Make sure there are no mappings in the MSIX MMIO areas, so that accesses
+     * can be trapped (and emulated) by Xen when the memory decoding bit is
+     * enabled.
+     *
+     * FIXME: punching holes after the p2m has been set up might be racy for
+     * DomU usage, needs to be revisited.
+     */
+    if ( map && !rom_only && vpci_make_msix_hole(pdev) )
+        return;
+
     for ( i = 0; i < ARRAY_SIZE(header->bars); i++ )
     {
         if ( !MAPPABLE_BAR(&header->bars[i]) )
diff --git a/xen/drivers/vpci/msix.c b/xen/drivers/vpci/msix.c
index 1960dae123..af3ffa087d 100644
--- a/xen/drivers/vpci/msix.c
+++ b/xen/drivers/vpci/msix.c
@@ -21,6 +21,7 @@
 #include <xen/vpci.h>
 
 #include <asm/msi.h>
+#include <asm/p2m.h>
 
 #define VMSIX_SIZE(num) offsetof(struct vpci_msix, entries[num])
 
@@ -395,6 +396,54 @@ static const struct hvm_mmio_ops vpci_msix_table_ops = {
     .write = msix_write,
 };
 
+int vpci_make_msix_hole(const struct pci_dev *pdev)
+{
+    struct domain *d = pdev->domain;
+    unsigned int i;
+
+    if ( !pdev->vpci->msix )
+        return 0;
+
+    /* Make sure there's a hole for the MSIX table/PBA in the p2m. */
+    for ( i = 0; i < ARRAY_SIZE(pdev->vpci->msix->tables); i++ )
+    {
+        unsigned long start = PFN_DOWN(vmsix_table_addr(pdev->vpci, i));
+        unsigned long end = PFN_DOWN(vmsix_table_addr(pdev->vpci, i) +
+                                     vmsix_table_size(pdev->vpci, i) - 1);
+
+        for ( ; start <= end; start++ )
+        {
+            p2m_type_t t;
+            mfn_t mfn = get_gfn_query(d, start, &t);
+
+            switch ( t )
+            {
+            case p2m_mmio_dm:
+            case p2m_invalid:
+                break;
+            case p2m_mmio_direct:
+                if ( mfn_x(mfn) == start )
+                {
+                    clear_identity_p2m_entry(d, start);
+                    break;
+                }
+                /* fallthrough. */
+            default:
+                put_gfn(d, start);
+                gprintk(XENLOG_WARNING,
+                        "%04x:%02x:%02x.%u: existing mapping (mfn: %" PRI_mfn
+                        "type: %d) at %#lx clobbers MSIX MMIO area\n",
+                        pdev->seg, pdev->bus, PCI_SLOT(pdev->devfn),
+                        PCI_FUNC(pdev->devfn), mfn_x(mfn), t, start);
+                return -EEXIST;
+            }
+            put_gfn(d, start);
+        }
+    }
+
+    return 0;
+}
+
 static int init_msix(struct pci_dev *pdev)
 {
     struct domain *d = pdev->domain;
diff --git a/xen/include/xen/vpci.h b/xen/include/xen/vpci.h
index 44104b75b6..4cf233c779 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -152,6 +152,9 @@ struct vpci_vcpu {
 #ifdef __XEN__
 void vpci_dump_msi(void);
 
+/* Make sure there's a hole in the p2m for the MSIX mmio areas. */
+int vpci_make_msix_hole(const struct pci_dev *pdev);
+
 /* Arch-specific vPCI MSI helpers. */
 void vpci_msi_arch_mask(struct vpci_msi *msi, const struct pci_dev *pdev,
                         unsigned int entry, bool mask);
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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