With our switching away from supporting 32-bit Dom0 operation, users
complained that attempts (perhaps due to lack of knowledge of that
change) to boot the no longer privileged kernel in Dom0 resulted in
apparently silent failure. To make the mismatch explicit and visible,
add feature flags that the kernel can set to indicate operation in
what modes it supports. For backward compatibility, absence of both
feature flags is taken to indicate a kernel that may be capable of
operating in both modes.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
--- a/tools/libxc/xc_dom_elfloader.c
+++ b/tools/libxc/xc_dom_elfloader.c
@@ -286,6 +286,15 @@ static int xc_dom_parse_elf_kernel(struc
if ( (rc = elf_xen_parse(elf, &dom->parms)) != 0 )
return rc;
+ if ( elf_xen_feature_get(XENFEAT_privileged, dom->parms.f_required) ||
+ (elf_xen_feature_get(XENFEAT_privileged, dom->parms.f_supported) &&
+ !elf_xen_feature_get(XENFEAT_unprivileged, dom->parms.f_supported)) )
+ {
+ xc_dom_panic(dom->xch, XC_INVALID_KERNEL, "%s: Kernel does not"
+ " support unprivileged (DomU) operation", __FUNCTION__);
+ return -EINVAL;
+ }
+
/* find kernel segment */
dom->kernel_seg.vstart = dom->parms.virt_kstart;
dom->kernel_seg.vend = dom->parms.virt_kend;
--- a/xen/arch/ia64/xen/domain.c
+++ b/xen/arch/ia64/xen/domain.c
@@ -2164,6 +2164,14 @@ int __init construct_dom0(struct domain
return -1;
}
+ if (test_bit(XENFEAT_unprivileged, parms.f_required) ||
+ (test_bit(XENFEAT_unprivileged, parms.f_supported) &&
+ !test_bit(XENFEAT_privileged, parms.f_supported)))
+ {
+ printk("Kernel does not support Dom0 operation\n");
+ return -1;
+ }
+
p_start = parms.virt_base;
pkern_start = parms.virt_kstart;
pkern_end = parms.virt_kend;
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -415,6 +415,14 @@ int __init construct_dom0(
return -EINVAL;
}
+ if ( test_bit(XENFEAT_unprivileged, parms.f_required) ||
+ (test_bit(XENFEAT_unprivileged, parms.f_supported) &&
+ !test_bit(XENFEAT_privileged, parms.f_supported)) )
+ {
+ printk("Kernel does not support Dom0 operation\n");
+ return -EINVAL;
+ }
+
#if defined(__x86_64__)
if ( compat32 )
{
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -278,7 +278,8 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDL
switch ( fi.submap_idx )
{
case 0:
- fi.submap = 0;
+ fi.submap = 1U << (IS_PRIV(current->domain) ?
+ XENFEAT_privileged : XENFEAT_unprivileged);
if ( VM_ASSIST(d, VMASST_TYPE_pae_extended_cr3) )
fi.submap |= (1U << XENFEAT_pae_pgdir_above_4gb);
if ( paging_mode_translate(current->domain) )
--- a/xen/common/libelf/libelf-dominfo.c
+++ b/xen/common/libelf/libelf-dominfo.c
@@ -26,7 +26,9 @@ static const char *const elf_xen_feature
[XENFEAT_writable_descriptor_tables] = "writable_descriptor_tables",
[XENFEAT_auto_translated_physmap] = "auto_translated_physmap",
[XENFEAT_supervisor_mode_kernel] = "supervisor_mode_kernel",
- [XENFEAT_pae_pgdir_above_4gb] = "pae_pgdir_above_4gb"
+ [XENFEAT_pae_pgdir_above_4gb] = "pae_pgdir_above_4gb",
+ [XENFEAT_privileged] = "privileged",
+ [XENFEAT_unprivileged] = "unprivileged"
};
static const int elf_xen_features =
sizeof(elf_xen_feature_names) / sizeof(elf_xen_feature_names[0]);
--- a/xen/include/public/features.h
+++ b/xen/include/public/features.h
@@ -75,7 +75,13 @@
#define XENFEAT_hvm_safe_pvclock 9
/* x86: pirq can be used by HVM guests */
-#define XENFEAT_hvm_pirqs 10
+#define XENFEAT_hvm_pirqs 10
+
+/* privileged operation is supported */
+#define XENFEAT_privileged 11
+
+/* un-privileged operation is supported */
+#define XENFEAT_unprivileged 12
#define XENFEAT_NR_SUBMAPS 1
guest-kernel-cap.patch
Description: Text document
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