[Xen-devel] [PATCH v4 28/31] libxc/xen: introduce HVM_PARAM_CMDLINE_PFN

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

This HVM parameter returns a PFN that contains the address of the memory
page where the guest command line has been placed.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 tools/libxc/xc_dom_x86.c        | 17 +++++++++++++++++
 xen/arch/x86/hvm/hvm.c          |  2 ++
 xen/include/public/hvm/params.h |  5 ++++-
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
index 87bce6e..369745d 100644
--- a/tools/libxc/xc_dom_x86.c
+++ b/tools/libxc/xc_dom_x86.c
@@ -562,6 +562,23 @@ static int alloc_magic_pages_hvm(struct xc_dom_image *dom)
     xc_hvm_param_set(xch, domid, HVM_PARAM_SHARING_RING_PFN,
                      special_pfn(SPECIALPAGE_SHARING));
 
+    if ( dom->cmdline )
+    {
+        xen_pfn_t cmdline_pfn = xc_dom_alloc_page(dom, "command line");
+        char *cmdline = xc_map_foreign_range(xch, domid, PAGE_SIZE,
+                                             PROT_READ | PROT_WRITE,
+                                             cmdline_pfn);
+        if ( cmdline == NULL ) {
+            DOMPRINTF("Unable to map command line page");
+            goto error_out;
+        }
+
+        strncpy(cmdline, dom->cmdline, MAX_GUEST_CMDLINE);
+        cmdline[MAX_GUEST_CMDLINE - 1] = '\0';
+        munmap(cmdline, PAGE_SIZE);
+        xc_hvm_param_set(xch, domid, HVM_PARAM_CMDLINE_PFN, cmdline_pfn);
+    }
+
     if ( dom->emulation )
     {
         /*
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 15ea5e2..615ea30 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -5866,6 +5866,7 @@ static int hvm_allow_set_param(struct domain *d,
     case HVM_PARAM_VM_GENERATION_ID_ADDR:
     case HVM_PARAM_STORE_EVTCHN:
     case HVM_PARAM_CONSOLE_EVTCHN:
+    case HVM_PARAM_CMDLINE_PFN:
         break;
     /*
      * The following parameters must not be set by the guest
@@ -6097,6 +6098,7 @@ static int hvm_allow_get_param(struct domain *d,
     case HVM_PARAM_CONSOLE_PFN:
     case HVM_PARAM_CONSOLE_EVTCHN:
     case HVM_PARAM_ALTP2M:
+    case HVM_PARAM_CMDLINE_PFN:
         break;
     /*
      * The following parameters must not be read by the guest
diff --git a/xen/include/public/hvm/params.h b/xen/include/public/hvm/params.h
index 147d9b8..aa926d4 100644
--- a/xen/include/public/hvm/params.h
+++ b/xen/include/public/hvm/params.h
@@ -190,6 +190,9 @@
 /* Boolean: Enable altp2m */
 #define HVM_PARAM_ALTP2M       35
 
-#define HVM_NR_PARAMS          36
+/* PFN of the command line. */
+#define HVM_PARAM_CMDLINE_PFN 36
+
+#define HVM_NR_PARAMS          37
 
 #endif /* __XEN_PUBLIC_HVM_PARAMS_H__ */
-- 
1.9.5 (Apple Git-50.3)


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