hvc_xen: support PV on HVM consoles

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

2 files changed, 73 insertions, 17 deletions

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 52fdf60bdbe2..d5000aa02864 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -24,9 +24,12 @@
 #include <linux/init.h>
 #include <linux/types.h>
 
+#include <asm/io.h>
 #include <asm/xen/hypervisor.h>
 
 #include <xen/xen.h>
+#include <xen/interface/xen.h>
+#include <xen/hvm.h>
 #include <xen/page.h>
 #include <xen/events.h>
 #include <xen/interface/io/console.h>
@@ -42,9 +45,13 @@ static int xencons_irq;
 /* ------------------------------------------------------------------ */
 
 static unsigned long console_pfn = ~0ul;
+static unsigned int console_evtchn = ~0ul;
+static struct xencons_interface *xencons_if = NULL;
 
 static inline struct xencons_interface *xencons_interface(void)
 {
+        if (xencons_if != NULL)
+                return xencons_if;
         if (console_pfn == ~0ul)
                 return mfn_to_virt(xen_start_info->console.domU.mfn);
         else
@@ -54,7 +61,10 @@ static inline struct xencons_interface *xencons_interface(void)
 static inline void notify_daemon(void)
 {
         /* Use evtchn: this is called early, before irq is set up. */
-        notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
+        if (console_evtchn == ~0ul)
+                notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
+        else
+                notify_remote_via_evtchn(console_evtchn);
 }
 
 static int __write_console(const char *data, int len)
@@ -157,28 +167,63 @@ static struct hv_ops dom0_hvc_ops = {
         .notifier_hangup = notifier_hangup_irq,
 };
 
+static int xen_hvm_console_init(void)
+{
+        int r;
+        uint64_t v = 0;
+        unsigned long mfn;
+
+        if (!xen_hvm_domain())
+                return -ENODEV;
+
+        if (xencons_if != NULL)
+                return -EBUSY;
+
+        r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
+        if (r < 0)
+                return -ENODEV;
+        console_evtchn = v;
+        hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
+        if (r < 0)
+                return -ENODEV;
+        mfn = v;
+        xencons_if = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
+        if (xencons_if == NULL)
+                return -ENODEV;
+
+        return 0;
+}
+
 static int __init xen_hvc_init(void)
 {
         struct hvc_struct *hp;
         struct hv_ops *ops;
+        int r;
 
-        if (!xen_pv_domain())
+        if (!xen_domain())
                 return -ENODEV;
 
         if (xen_initial_domain()) {
                 ops = &dom0_hvc_ops;
                 xencons_irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
         } else {
-                if (!xen_start_info->console.domU.evtchn)
-                        return -ENODEV;
-
                 ops = &domU_hvc_ops;
-                xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
+                if (xen_pv_domain()) {
+                        if (!xen_start_info->console.domU.evtchn)
+                                return -ENODEV;
+                        console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
+                        console_evtchn = xen_start_info->console.domU.evtchn;
+                } else {
+                        r = xen_hvm_console_init();
+                        if (r < 0)
+                                return r;
+                }
+                xencons_irq = bind_evtchn_to_irq(console_evtchn);
+                if (xencons_irq < 0)
+                        xencons_irq = 0; /* NO_IRQ */
+                else
+                        irq_set_noprobe(xencons_irq);
         }
-        if (xencons_irq < 0)
-                xencons_irq = 0; /* NO_IRQ */
-        else
-                irq_set_noprobe(xencons_irq);
 
         hp = hvc_alloc(HVC_COOKIE, xencons_irq, ops, 256);
         if (IS_ERR(hp))
@@ -186,15 +231,13 @@ static int __init xen_hvc_init(void)
 
         hvc = hp;
 
-        console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
-
         return 0;
 }
 
 void xen_console_resume(void)
 {
         if (xencons_irq)
-                rebind_evtchn_irq(xen_start_info->console.domU.evtchn, xencons_irq);
+                rebind_evtchn_irq(console_evtchn, xencons_irq);
 }
 
 static void __exit xen_hvc_fini(void)
@@ -205,16 +248,22 @@ static void __exit xen_hvc_fini(void)
 
 static int xen_cons_init(void)
 {
-        struct hv_ops *ops;
+        const struct hv_ops *ops;
 
-        if (!xen_pv_domain())
+        if (!xen_domain())
                 return 0;
 
         if (xen_initial_domain())
                 ops = &dom0_hvc_ops;
-        else
+        else {
                 ops = &domU_hvc_ops;
 
+                if (xen_pv_domain())
+                        console_evtchn = xen_start_info->console.domU.evtchn;
+                else
+                        xen_hvm_console_init();
+        }
+
         hvc_instantiate(HVC_COOKIE, 0, ops);
         return 0;
 }
@@ -230,6 +279,9 @@ static void xenboot_write_console(struct console *console, const char *string,
         unsigned int linelen, off = 0;
         const char *pos;
 
+        if (!xen_pv_domain())
+                return;
+
         dom0_write_console(0, string, len);
 
         if (xen_initial_domain())
diff --git a/include/xen/interface/hvm/params.h b/include/xen/interface/hvm/params.h
index 1888d8c157e6..1b4f923d7086 100644
--- a/include/xen/interface/hvm/params.h
+++ b/include/xen/interface/hvm/params.h
@@ -90,6 +90,10 @@
 /* Boolean: Enable aligning all periodic vpts to reduce interrupts */
 #define HVM_PARAM_VPT_ALIGN    16
 
-#define HVM_NR_PARAMS          17
+/* Console debug shared memory ring and event channel */
+#define HVM_PARAM_CONSOLE_PFN    17
+#define HVM_PARAM_CONSOLE_EVTCHN 18
+
+#define HVM_NR_PARAMS          19
 
 #endif /* __XEN_PUBLIC_HVM_PARAMS_H__ */