0622-libxl-check-control-feature-before-issuing-pvcontrol.patch

From 4b602273b9d179ef2c375c7db7d3d1fbb9546c9f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
 <marmarek@invisiblethingslab.com>
Date: Thu, 27 Oct 2022 21:27:05 +0200
Subject: [PATCH 22/26] libxl: check control/feature-* before issuing pvcontrol
 command
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Content-Type: text/plain; charset=UTF-8
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Check early, instead of waiting for a timeout. This is relevant for
example for Mirage OS PVH domain, which doesn't support suspend.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
---
 tools/libs/light/libxl_domain.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/libs/light/libxl_domain.c b/tools/libs/light/libxl_domain.c
index 6451b4a145ee..0d5d1ef6663c 100644
--- a/tools/libs/light/libxl_domain.c
+++ b/tools/libs/light/libxl_domain.c
@@ -777,6 +777,7 @@ int libxl__domain_pvcontrol(libxl__egc *egc, libxl__xswait_state *pvcontrol,
     struct xs_permissions perms[] = {
         { .id = domid, .perms = XS_PERM_NONE },
     };
+    char *feature;
     int rc;
 
     rc = libxl__domain_pvcontrol_available(gc, domid);
@@ -795,6 +796,15 @@ int libxl__domain_pvcontrol(libxl__egc *egc, libxl__xswait_state *pvcontrol,
     if (!t)
         return ERROR_FAIL;
 
+    feature = libxl__xs_read(gc, t, GCSPRINTF("%s/control/feature-%s",
+                                              libxl__xs_get_dompath(gc, domid),
+                                              cmd));
+    if (!feature || strcmp(feature, "1")) {
+        LOGD(ERROR, domid, "PV control '%s' not supported by this domain", cmd);
+        xs_transaction_end(ctx->xsh, t, 1);
+        return ERROR_NOPARAVIRT;
+    }
+
     rc = libxl__xs_printf(gc, t, shutdown_path, "%s", cmd);
     if (rc) {
         xs_transaction_end(ctx->xsh, t, 1);
-- 
2.37.3