xen/pt: allow QEMU to request MSI unmasking at bind time

When a MSI interrupt is bound to a guest using
xc_domain_update_msi_irq (XEN_DOMCTL_bind_pt_irq) the interrupt is
left masked by default.

This causes problems with guests that first configure interrupts and
clean the per-entry MSIX table mask bit and afterwards enable MSIX
globally. In such scenario the Xen internal msixtbl handlers would not
detect the unmasking of MSIX entries because vectors are not yet
registered since MSIX is not enabled, and vectors would be left
masked.

Introduce a new flag in the gflags field to signal Xen whether a MSI
interrupt should be unmasked after being bound.

This also requires to track the mask register for MSI interrupts, so
QEMU can also notify to Xen whether the MSI interrupt should be bound
masked or unmasked

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reported-by: Andreas Kinzler <hfp@posteo.de>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
(cherry picked from commit a8036336609d2e184fc3543a4c439c0ba7d7f3a2)
Release-acked-by: Julien Grall <julien.grall@linaro.org>

diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
index 191d9caea1450faedc3468d74ab0bbcaf5efc452..aa39a9aa5f3f8df5014b27aaa78ffdaadbf3392c 100644 (file)
--- a/hw/xen/xen_pt.h
+++ b/hw/xen/xen_pt.h
@@ -180,6 +180,7 @@ typedef struct XenPTMSI {
     uint32_t addr_hi;  /* guest message upper address */
     uint16_t data;     /* guest message data */
     uint32_t ctrl_offset; /* saved control offset */
+    uint32_t mask;     /* guest mask bits */
     int pirq;          /* guest pirq corresponding */
     bool initialized;  /* when guest MSI is initialized */
     bool mapped;       /* when pirq is mapped */

diff --git a/hw/xen/xen_pt_config_init.c b/hw/xen/xen_pt_config_init.c
index 1f04ec5eecb48b3be3ddbe29695e78dafed973ae..a3ce33e78b569fc3f4224c2c4cdb957f87645c23 100644 (file)
--- a/hw/xen/xen_pt_config_init.c
+++ b/hw/xen/xen_pt_config_init.c
@@ -1315,6 +1315,22 @@ static int xen_pt_msgdata_reg_write(XenPCIPassthroughState *s,
     return 0;
 }
 
+static int xen_pt_mask_reg_write(XenPCIPassthroughState *s, XenPTReg *cfg_entry,
+                                 uint32_t *val, uint32_t dev_value,
+                                 uint32_t valid_mask)
+{
+    int rc;
+
+    rc = xen_pt_long_reg_write(s, cfg_entry, val, dev_value, valid_mask);
+    if (rc) {
+        return rc;
+    }
+
+    s->msi->mask = *val;
+
+    return 0;
+}
+
 /* MSI Capability Structure reg static information table */
 static XenPTRegInfo xen_pt_emu_reg_msi[] = {
     /* Next Pointer reg */
@@ -1393,7 +1409,7 @@ static XenPTRegInfo xen_pt_emu_reg_msi[] = {
         .emu_mask   = 0xFFFFFFFF,
         .init       = xen_pt_mask_reg_init,
         .u.dw.read  = xen_pt_long_reg_read,
-        .u.dw.write = xen_pt_long_reg_write,
+        .u.dw.write = xen_pt_mask_reg_write,
     },
     /* Mask reg (if PCI_MSI_FLAGS_MASKBIT set, for 64-bit devices) */
     {
@@ -1404,7 +1420,7 @@ static XenPTRegInfo xen_pt_emu_reg_msi[] = {
         .emu_mask   = 0xFFFFFFFF,
         .init       = xen_pt_mask_reg_init,
         .u.dw.read  = xen_pt_long_reg_read,
-        .u.dw.write = xen_pt_long_reg_write,
+        .u.dw.write = xen_pt_mask_reg_write,
     },
     /* Pending reg (if PCI_MSI_FLAGS_MASKBIT set, for 32-bit devices) */
     {

diff --git a/hw/xen/xen_pt_msi.c b/hw/xen/xen_pt_msi.c
index ff9a79f5d27ad7d74a1b22297be560feb455063c..6d1e3bdeb47dbf8ea251d66ae4755bdceed2bc07 100644 (file)
--- a/hw/xen/xen_pt_msi.c
+++ b/hw/xen/xen_pt_msi.c
@@ -24,6 +24,7 @@
 #define XEN_PT_GFLAGS_SHIFT_DM             9
 #define XEN_PT_GFLAGSSHIFT_DELIV_MODE     12
 #define XEN_PT_GFLAGSSHIFT_TRG_MODE       15
+#define XEN_PT_GFLAGSSHIFT_UNMASKED       16
 
 #define latch(fld) latch[PCI_MSIX_ENTRY_##fld / sizeof(uint32_t)]
 
@@ -155,7 +156,8 @@ static int msi_msix_update(XenPCIPassthroughState *s,
                            int pirq,
                            bool is_msix,
                            int msix_entry,
-                           int *old_pirq)
+                           int *old_pirq,
+                           bool masked)
 {
     PCIDevice *d = &s->dev;
     uint8_t gvec = msi_vector(data);
@@ -171,6 +173,8 @@ static int msi_msix_update(XenPCIPassthroughState *s,
         table_addr = s->msix->mmio_base_addr;
     }
 
+    gflags |= masked ? 0 : (1u << XEN_PT_GFLAGSSHIFT_UNMASKED);
+
     rc = xc_domain_update_msi_irq(xen_xc, xen_domid, gvec,
                                   pirq, gflags, table_addr);
 
@@ -273,8 +277,10 @@ int xen_pt_msi_setup(XenPCIPassthroughState *s)
 int xen_pt_msi_update(XenPCIPassthroughState *s)
 {
     XenPTMSI *msi = s->msi;
+
+    /* Current MSI emulation in QEMU only supports 1 vector */
     return msi_msix_update(s, msi_addr64(msi), msi->data, msi->pirq,
-                           false, 0, &msi->pirq);
+                           false, 0, &msi->pirq, msi->mask & 1);
 }
 
 void xen_pt_msi_disable(XenPCIPassthroughState *s)
@@ -355,7 +361,8 @@ static int xen_pt_msix_update_one(XenPCIPassthroughState *s, int entry_nr,
     }
 
     rc = msi_msix_update(s, entry->addr, entry->data, pirq, true,
-                         entry_nr, &entry->pirq);
+                         entry_nr, &entry->pirq,
+                         vec_ctrl & PCI_MSIX_ENTRY_CTRL_MASKBIT);
 
     if (!rc) {
         entry->updated = false;