[Xen-devel] [PATCH 1/2] hvc_xen: support PV on HVM consoles

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 drivers/tty/hvc/hvc_xen.c          |   86 +++++++++++++++++++++++++++++-------
 include/xen/interface/hvm/params.h |    6 ++-
 2 files changed, 75 insertions(+), 17 deletions(-)

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 52fdf60..dd6641f 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 +167,65 @@ 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_pv_domain() && !xen_initial_domain() &&
+                       !xen_start_info->console.domU.evtchn)
                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()) {
+                       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 +233,13 @@ 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 +250,22 @@ 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 +281,9 @@ 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 1888d8c..1b4f923 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__ */
-- 
1.7.2.5


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