Re: [RFC PATCH v1 23/25] hw/xen: Map guest XENSTORE_PFN grant in emulated Xenstore

2023-03-07 Thread Paul Durrant 

On 02/03/2023 15:34, David Woodhouse wrote:

From: David Woodhouse 

Signed-off-by: David Woodhouse 
---
  hw/i386/kvm/xen_xenstore.c | 16 
  1 file changed, 16 insertions(+)

diff --git a/hw/i386/kvm/xen_xenstore.c b/hw/i386/kvm/xen_xenstore.c
index 028f80499e..f9b7387024 100644
--- a/hw/i386/kvm/xen_xenstore.c
+++ b/hw/i386/kvm/xen_xenstore.c
@@ -21,6 +21,7 @@
  
  #include "hw/sysbus.h"

  #include "hw/xen/xen.h"
+#include "hw/xen/xen_backend_ops.h"
  #include "xen_overlay.h"
  #include "xen_evtchn.h"
  #include "xen_xenstore.h"
@@ -34,6 +35,7 @@
  
  #include "hw/xen/interface/io/xs_wire.h"

  #include "hw/xen/interface/event_channel.h"
+#include "hw/xen/interface/grant_table.h"
  
  #define TYPE_XEN_XENSTORE "xen-xenstore"

  OBJECT_DECLARE_SIMPLE_TYPE(XenXenstoreState, XEN_XENSTORE)
@@ -66,6 +68,9 @@ struct XenXenstoreState {
  
  uint8_t *impl_state;

  uint32_t impl_state_size;
+
+struct xengntdev_handle *gt;
+void *granted_xs;
  };
  
  struct XenXenstoreState *xen_xenstore_singleton;

@@ -1452,6 +1457,17 @@ int xen_xenstore_reset(void)
  }
  s->be_port = err;
  
+/*

+ * We don't actually access the guest's page through the grant, because
+ * this isn't real Xen, and we can just use the page we gave it in the
+ * first place. Map the grant anyway, mostly for cosmetic purposes so
+ * it *looks* like it's in use in the guest-visible grant table.


Might be useful to stick this text in the commit comment too.

Reviewed-by: Paul Durrant 


+ */
+s->gt = qemu_xen_gnttab_open();
+uint32_t xs_gntref = GNTTAB_RESERVED_XENSTORE;
+s->granted_xs = qemu_xen_gnttab_map_refs(s->gt, 1, xen_domid, _gntref,
+ PROT_READ | PROT_WRITE);
+
  return 0;
  }

[RFC PATCH v1 23/25] hw/xen: Map guest XENSTORE_PFN grant in emulated Xenstore

2023-03-02 Thread David Woodhouse 
From: David Woodhouse 

Signed-off-by: David Woodhouse 
---
 hw/i386/kvm/xen_xenstore.c | 16 
 1 file changed, 16 insertions(+)

diff --git a/hw/i386/kvm/xen_xenstore.c b/hw/i386/kvm/xen_xenstore.c
index 028f80499e..f9b7387024 100644
--- a/hw/i386/kvm/xen_xenstore.c
+++ b/hw/i386/kvm/xen_xenstore.c
@@ -21,6 +21,7 @@
 
 #include "hw/sysbus.h"
 #include "hw/xen/xen.h"
+#include "hw/xen/xen_backend_ops.h"
 #include "xen_overlay.h"
 #include "xen_evtchn.h"
 #include "xen_xenstore.h"
@@ -34,6 +35,7 @@
 
 #include "hw/xen/interface/io/xs_wire.h"
 #include "hw/xen/interface/event_channel.h"
+#include "hw/xen/interface/grant_table.h"
 
 #define TYPE_XEN_XENSTORE "xen-xenstore"
 OBJECT_DECLARE_SIMPLE_TYPE(XenXenstoreState, XEN_XENSTORE)
@@ -66,6 +68,9 @@ struct XenXenstoreState {
 
 uint8_t *impl_state;
 uint32_t impl_state_size;
+
+struct xengntdev_handle *gt;
+void *granted_xs;
 };
 
 struct XenXenstoreState *xen_xenstore_singleton;
@@ -1452,6 +1457,17 @@ int xen_xenstore_reset(void)
 }
 s->be_port = err;
 
+/*
+ * We don't actually access the guest's page through the grant, because
+ * this isn't real Xen, and we can just use the page we gave it in the
+ * first place. Map the grant anyway, mostly for cosmetic purposes so
+ * it *looks* like it's in use in the guest-visible grant table.
+ */
+s->gt = qemu_xen_gnttab_open();
+uint32_t xs_gntref = GNTTAB_RESERVED_XENSTORE;
+s->granted_xs = qemu_xen_gnttab_map_refs(s->gt, 1, xen_domid, _gntref,
+ PROT_READ | PROT_WRITE);
+
 return 0;
 }
 
-- 
2.39.0