1 files changed, 122 insertions, 0 deletions
diff --git a/sysutils/xen-tools/files/xsa131-qemuu-8.patch b/sysutils/xen-tools/files/xsa131-qemuu-8.patch
new file mode 100644
index 000000000000..9537baf27d50
--- /dev/null
+++ b/sysutils/xen-tools/files/xsa131-qemuu-8.patch
@@ -0,0 +1,122 @@
+xen/pt: unknown PCI config space fields should be read-only
+
+... by default. Add a per-device "permissive" mode similar to pciback's
+to allow restoring previous behavior (and hence break security again,
+i.e. should be used only for trusted guests).
+
+This is part of XSA-131.
+
+Signed-off-by: Jan Beulich <jbeulich@suse.com>
+Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
+Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>)
+---
+Notes:
+- What purpose does xen_pt_header_type_reg_init() serve (with .emu_mask
+  being zero)?
+- In the qemu-trad case no equivalent logic to that setting/using
+  direct_pci_{msi_translate,power_mgmt} is being added, as that logic
+  seems broken (setting globals from device 0 xenstore settings).
+
+--- a/hw/xen/xen_pt.c
++++ b/hw/xen/xen_pt.c
+@@ -239,6 +239,7 @@ static void xen_pt_pci_write_config(PCID
+     XenPTReg *reg_entry = NULL;
+     uint32_t find_addr = addr;
+     XenPTRegInfo *reg = NULL;
++    bool wp_flag = false;
+ 
+     if (xen_pt_pci_config_access_check(d, addr, len)) {
+         return;
+@@ -280,6 +281,10 @@ static void xen_pt_pci_write_config(PCID
+ 
+     /* pass directly to the real device for passthrough type register group */
+     if (reg_grp_entry == NULL) {
++        if (!s->permissive) {
++            wb_mask = 0;
++            wp_flag = true;
++        }
+         goto out;
+     }
+ 
+@@ -300,12 +305,15 @@ static void xen_pt_pci_write_config(PCID
+             uint32_t real_offset = reg_grp_entry->base_offset + reg->offset;
+             uint32_t valid_mask = 0xFFFFFFFF >> ((4 - emul_len) << 3);
+             uint8_t *ptr_val = NULL;
++            uint32_t wp_mask = reg->emu_mask | reg->ro_mask;
+ 
+             valid_mask <<= (find_addr - real_offset) << 3;
+             ptr_val = (uint8_t *)&val + (real_offset & 3);
+-            if (reg->emu_mask == (0xFFFFFFFF >> ((4 - reg->size) << 3))) {
+-                wb_mask &= ~((reg->emu_mask
+-                              >> ((find_addr - real_offset) << 3))
++            if (!s->permissive) {
++                wp_mask |= reg->res_mask;
++            }
++            if (wp_mask == (0xFFFFFFFF >> ((4 - reg->size) << 3))) {
++                wb_mask &= ~((wp_mask >> ((find_addr - real_offset) << 3))
+                              << ((len - emul_len) << 3));
+             }
+ 
+@@ -349,6 +357,16 @@ static void xen_pt_pci_write_config(PCID
+         } else {
+             /* nothing to do with passthrough type register,
+              * continue to find next byte */
++            if (!s->permissive) {
++                wb_mask &= ~(0xff << ((len - emul_len) << 3));
++                /* Unused BARs will make it here, but we don't want to issue
++                 * warnings for writes to them (bogus writes get dealt with
++                 * above).
++                 */
++                if (index < 0) {
++                    wp_flag = true;
++                }
++            }
+             emul_len--;
+             find_addr++;
+         }
+@@ -360,6 +378,13 @@ static void xen_pt_pci_write_config(PCID
+     memory_region_transaction_commit();
+ 
+ out:
++    if (wp_flag && !s->permissive_warned) {
++        s->permissive_warned = true;
++        xen_pt_log(d, "Write-back to unknown field 0x%02x (partially) inhibited (0x%0*x)\n",
++                   addr, len * 2, wb_mask);
++        xen_pt_log(d, "If the device doesn't work, try enabling permissive mode\n");
++        xen_pt_log(d, "(unsafe) and if it helps report the problem to xen-devel\n");
++    }
+     for (index = 0; wb_mask; index += len) {
+         /* unknown regs are passed through */
+         while (!(wb_mask & 0xff)) {
+@@ -821,6 +846,7 @@ static void xen_pt_unregister_device(PCI
+ 
+ static Property xen_pci_passthrough_properties[] = {
+     DEFINE_PROP_PCI_HOST_DEVADDR("hostaddr", XenPCIPassthroughState, hostaddr),
++    DEFINE_PROP_BOOL("permissive", XenPCIPassthroughState, permissive, false),
+     DEFINE_PROP_END_OF_LIST(),
+ };
+ 
+--- a/hw/xen/xen_pt.h
++++ b/hw/xen/xen_pt.h
+@@ -197,6 +197,8 @@ struct XenPCIPassthroughState {
+ 
+     PCIHostDeviceAddress hostaddr;
+     bool is_virtfn;
++    bool permissive;
++    bool permissive_warned;
+     XenHostPCIDevice real_device;
+     XenPTRegion bases[PCI_NUM_REGIONS]; /* Access regions */
+     QLIST_HEAD(, XenPTRegGroup) reg_grps;
+--- a/hw/xen/xen_pt_config_init.c
++++ b/hw/xen/xen_pt_config_init.c
+@@ -101,6 +101,10 @@ static uint32_t get_throughable_mask(con
+ {
+     uint32_t throughable_mask = ~(reg->emu_mask | reg->ro_mask);
+ 
++    if (!s->permissive) {
++        throughable_mask &= ~reg->res_mask;
++    }
++
+     return throughable_mask & valid_mask;
+ }
+