[Xen-devel] [PATCH v2 1/4] x86/dom0: prevent access to MMCFG areas for PVH Dom0

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

They are emulated by Xen, so they must not be mapped into Dom0 p2m.
Introduce a helper function to add the MMCFG areas to the list of
denied iomem regions for PVH Dom0.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
Changes since RFC:
 - Introduce as helper instead of exposing the internal mmcfg
   variables to the Dom0 builder.
---
 xen/arch/x86/dom0_build.c         |  4 ++++
 xen/arch/x86/x86_64/mmconfig_64.c | 21 +++++++++++++++++++++
 xen/include/xen/pci.h             |  2 ++
 3 files changed, 27 insertions(+)

diff --git a/xen/arch/x86/dom0_build.c b/xen/arch/x86/dom0_build.c
index 0c125e61eb..3e0910d779 100644
--- a/xen/arch/x86/dom0_build.c
+++ b/xen/arch/x86/dom0_build.c
@@ -440,6 +440,10 @@ int __init dom0_setup_permissions(struct domain *d)
             rc |= rangeset_add_singleton(mmio_ro_ranges, mfn);
     }
 
+    /* For PVH prevent access to the MMCFG areas. */
+    if ( dom0_pvh )
+        rc |= pci_mmcfg_set_domain_permissions(d);
+
     return rc;
 }
 
diff --git a/xen/arch/x86/x86_64/mmconfig_64.c 
b/xen/arch/x86/x86_64/mmconfig_64.c
index e84a67dfc4..271fad407f 100644
--- a/xen/arch/x86/x86_64/mmconfig_64.c
+++ b/xen/arch/x86/x86_64/mmconfig_64.c
@@ -15,6 +15,8 @@
 #include <xen/pci_regs.h>
 #include <xen/iommu.h>
 #include <xen/rangeset.h>
+#include <xen/sched.h>
+#include <xen/iocap.h>
 
 #include "mmconfig.h"
 
@@ -175,6 +177,25 @@ void pci_mmcfg_arch_disable(unsigned int idx)
            cfg->pci_segment, cfg->start_bus_number, cfg->end_bus_number);
 }
 
+int pci_mmcfg_set_domain_permissions(struct domain *d)
+{
+    unsigned int idx;
+    int rc = 0;
+
+    for ( idx = 0; idx < pci_mmcfg_config_num; idx++ )
+    {
+        const struct acpi_mcfg_allocation *cfg = pci_mmcfg_virt[idx].cfg;
+        unsigned long start = PFN_DOWN(cfg->address) +
+                              PCI_BDF(cfg->start_bus_number, 0, 0);
+        unsigned long end = PFN_DOWN(cfg->address) +
+                            PCI_BDF(cfg->end_bus_number, ~0, ~0);
+
+        rc |= iomem_deny_access(d, start, end);
+    }
+
+    return rc;
+}
+
 bool_t pci_mmcfg_decode(unsigned long mfn, unsigned int *seg,
                         unsigned int *bdf)
 {
diff --git a/xen/include/xen/pci.h b/xen/include/xen/pci.h
index 59b6e8a81c..ea6a66b248 100644
--- a/xen/include/xen/pci.h
+++ b/xen/include/xen/pci.h
@@ -170,4 +170,6 @@ int msixtbl_pt_register(struct domain *, struct pirq *, 
uint64_t gtable);
 void msixtbl_pt_unregister(struct domain *, struct pirq *);
 void msixtbl_pt_cleanup(struct domain *d);
 
+int pci_mmcfg_set_domain_permissions(struct domain *d);
+
 #endif /* __XEN_PCI_H__ */
-- 
2.11.0 (Apple Git-81)


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