[Xen-devel] [PATCH v3 10/18] xen: setup hypercall page for PVH

[Juergen Gross <jgross@xxxxxxxx>]

Add the needed code to setup the hypercall page for calling into the
Xen hypervisor.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V3: grub_xen_early_halt->grub_xen_panic (Roger Pau Monné)
    issue panic message (Roger Pau Monné)
    rewrite grub_xen_hypercall to avoid register variables (Daniel Kiper)
---
 grub-core/kern/i386/xen/pvh.c | 69 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)

diff --git a/grub-core/kern/i386/xen/pvh.c b/grub-core/kern/i386/xen/pvh.c
index ac6181f4e..7e90a4538 100644
--- a/grub-core/kern/i386/xen/pvh.c
+++ b/grub-core/kern/i386/xen/pvh.c
@@ -20,14 +20,83 @@
 #include <grub/misc.h>
 #include <grub/memory.h>
 #include <grub/mm.h>
+#include <grub/i386/cpuid.h>
+#include <grub/i386/io.h>
 #include <grub/xen.h>
 #include <grub/machine/kernel.h>
 
+#define XEN_CONSOLE_PORT   0xe9
+
 grub_uint64_t grub_rsdp_addr;
 
+static char hypercall_page[GRUB_XEN_PAGE_SIZE]
+  __attribute__ ((aligned (GRUB_XEN_PAGE_SIZE)));
+
+static grub_uint32_t xen_cpuid_base;
+
+static void
+grub_xen_panic (const char *msg)
+{
+  const char *c;
+
+  for (c = msg; *c; c++)
+    grub_outb (*c, XEN_CONSOLE_PORT);
+
+  asm volatile ("hlt");
+}
+
+static void
+grub_xen_cpuid_base (void)
+{
+  grub_uint32_t base, eax, signature[3];
+
+  for (base = 0x40000000; base < 0x40010000; base += 0x100)
+    {
+      grub_cpuid (base, eax, signature[0], signature[1], signature[2]);
+      if (!grub_memcmp ("XenVMMXenVMM", signature, 12) && (eax - base) >= 2)
+       {
+         xen_cpuid_base = base;
+         return;
+       }
+    }
+
+  grub_xen_panic ("Found no Xen signature.\n");
+}
+
+static void
+grub_xen_setup_hypercall_page (void)
+{
+  grub_uint32_t msr, pfn, eax, ebx, ecx, edx;
+
+  grub_cpuid (xen_cpuid_base + 2, eax, ebx, ecx, edx);
+  msr = ebx;
+  pfn = (grub_uint32_t) (&hypercall_page[0]);
+
+  asm volatile ("wrmsr" : : "c" (msr), "a" (pfn), "d" (0) : "memory");
+}
+
+int
+grub_xen_hypercall (grub_uint32_t callno, grub_uint32_t a0,
+                   grub_uint32_t a1, grub_uint32_t a2,
+                   grub_uint32_t a3, grub_uint32_t a4,
+                   grub_uint32_t a5 __attribute__ ((unused)))
+{
+  grub_uint32_t __res, __ign0, __ign1, __ign2, __ign3, __ign4;
+
+  asm volatile ("call *%[callno]"
+               : "=a" (__res), "=b" (__ign0), "=c" (__ign1), "=d" (__ign2),
+                 "=S" (__ign3), "=D" (__ign4)
+               : "1" (a0), "2" (a1), "3" (a2), "4" (a3), "5" (a4),
+                 [callno] "a" (&hypercall_page[callno * 32])
+               : "memory");
+  return __res;
+}
+
 void
 grub_xen_setup_pvh (void)
 {
+  grub_xen_cpuid_base ();
+  grub_xen_setup_hypercall_page ();
 }
 
 grub_err_t
-- 
2.16.4


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