Hi Andrew,
On 05/12/2019 22:30, Andrew Cooper wrote:
These hypercalls each use continue_hypercall_on_cpu(), whose API is about to
switch to use -ERESTART. Update the soon-to-be affected paths to cope,
folding existing contination logic where applicable.
In addition:
* For platform op and sysctl, insert a cpu_relax() into what is otherwise a
tight spinlock loop, and make the continuation logic common at the
epilogue.
* Contrary to the comment in the code, kexec_exec() does return in the
KEXEC_REBOOT case, needs to pass ret back to the caller.
It is not entirely trivial to me that KEXEC_REBOOT refers to
KEXEC_DEFAULT_TYPE. The more that if you look at the kexec_reboot()
helper, it will not return (see BUG()). What may return is
continue_hypercall_on_cpu().
So would it make sense to use KEXEC_DEFAULT_TYPE?
[...]
@@ -816,6 +819,13 @@ ret_t
do_platform_op(XEN_GUEST_HANDLE_PARAM(xen_platform_op_t) u_xenpf_op)
out:
spin_unlock(&xenpf_lock);
+ if ( ret == -ERESTART )
+ {
+ create_continuation:
Shall we indent create_continuation the same way as out?
[...]
@@ -1263,13 +1263,25 @@ static int do_kexec_op_internal(unsigned long op,
long do_kexec_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) uarg)
{
- return do_kexec_op_internal(op, uarg, 0);
+ int ret = do_kexec_op_internal(op, uarg, 0);
Shouldn't it be long (or unsigned long) here? Otherwise, the return of
hypercall_create_continuation() may be truncated.
+
+ if ( ret == -ERESTART )
+ ret = hypercall_create_continuation(__HYPERVISOR_kexec_op,
+ "lh", op, uarg);
+
+ return ret;
}
[...]
@@ -516,6 +519,12 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t)
u_sysctl)
__copy_to_guest(u_sysctl, op, 1) )
ret = -EFAULT;
+ if ( ret == -ERESTART )
+ {
+ create_continuation:
Similar question as the previous label create_continuation.
+ ret = hypercall_create_continuation(__HYPERVISOR_sysctl, "h",
u_sysctl);
+ }
+
return ret;
}
--
Julien Grall
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