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Re: [Xen-devel] [PATCH v3] kexec: implement STATUS hypercall to check if image is loaded
On 01/18/2017 04:47 AM, Wei Liu wrote:
On Wed, Jan 18, 2017 at 03:45:54AM -0700, Jan Beulich wrote:
On 18.01.17 at 11:37, <wei.liu2@xxxxxxxxxx> wrote:
On Wed, Jan 18, 2017 at 03:19:49AM -0700, Jan Beulich wrote:
On 17.01.17 at 18:29, <eric.devolder@xxxxxxxxxx> wrote:
--- a/xen/common/kexec.c
+++ b/xen/common/kexec.c
@@ -1169,6 +1169,22 @@ static int kexec_unload(XEN_GUEST_HANDLE_PARAM(void)
uarg)
return kexec_do_unload(&unload);
}
+static int kexec_status(XEN_GUEST_HANDLE_PARAM(void) uarg)
+{
+ xen_kexec_status_t status;
+ int base, bit;
+
+ if ( unlikely(copy_from_guest(&status, uarg, 1)) )
+ return -EFAULT;
+
+ /* No need to check KEXEC_FLAG_IN_PROGRESS. */
+
+ if ( kexec_load_get_bits(status.type, &base, &bit) )
+ return -EINVAL;
+
+ return test_bit(bit, &kexec_flags);
In the public header you promise to return zero or one here (unless
an error occurs), which requires the use of !!. Please see x86's
implementation of the function for how/when there can actually be
other non-zero values returned here (in particular all ones, which
would resolve to -EPERM).
--- a/xen/include/public/kexec.h
+++ b/xen/include/public/kexec.h
@@ -227,6 +227,19 @@ typedef struct xen_kexec_unload {
} xen_kexec_unload_t;
DEFINE_XEN_GUEST_HANDLE(xen_kexec_unload_t);
+/*
+ * Figure out whether we have an image loaded. A return value of
+ * zero indicates no image loaded. A return value of one
+ * indicates an image is loaded. A negative return value
+ * indicates an error.
+ *
+ * Type must be one of KEXEC_TYPE_DEFAULT or KEXEC_TYPE_CRASH.
+ */
+#define KEXEC_CMD_kexec_status 6
+typedef struct xen_kexec_status {
+ uint8_t type;
+} xen_kexec_status_t;
+DEFINE_XEN_GUEST_HANDLE(xen_kexec_status_t);
#else /* __XEN_INTERFACE_VERSION__ < 0x00040400 */
There was a blank line above here before your addition, and you
shouldn't eliminate it (making quickly scanning over the file harder).
I guess both items are simple enough to fix while committing.
Oops, I already committed this patch with Andrew's review. A follow-up
patch is appreciated. Thanks.
Well, I suppose that was directed at Eric ...
Yes. That was for Eric.
Wei.
Hi. I have made the two changes and recreated the entire patch.
It has been posted as v4.
If a delta patch against v3 was what was desired, then please
let me know and I'll provide.
Note my handling of the test_bit() scenario is to explicitly check
for return value of 1, so any value other than 1 returns 0.
Regards,
Eric
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