2017-03-20 17:18 GMT+01:00 Wei Liu <wei.l...@citrix.com>:
> On Mon, Mar 20, 2017 at 09:12:54AM +0100, Felix Schmoll wrote:
> > 2017-03-16 17:27 GMT+01:00 Wei Liu <wei.l...@citrix.com>:
> >
> > #undef COMP
> > diff --git a/xen/common/kernel.c b/xen/common/kernel.c
> > index 4b87c60845..de07ee529b 100644
> > --- a/xen/common/kernel.c
> > +++ b/xen/common/kernel.c
> > @@ -226,6 +226,12 @@ void __init do_initcalls(void)
> > * Simple hypercalls.
> > */
> >
> > +DO(domain_id)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
>
> XEN_GUEST_HANDLE_PARAM means arg is a pointer to void type inside of the
> guest, it's better to just use XEN_GUEST_HANDLE_PARAM(uint32_t) arg.
> Also see below.
>
> > +{
> > + struct domain *d = current->domain;
> > + return d->domain_id;
>
> You certainly don't need cmd, because you provide no command.
>
> If you want to return the domain id directly, you don't need arg.
> Also please be aware of the types (long vs uint32_t). I think this is
> the simplest approach.
>
> > +}
> > +
> > DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
> > {
> > bool_t deny = !!xsm_xen_version(XSM_OTHER, cmd);
> > diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
> > index 91ba8bb48e..4ad62aa01b 100644
> > --- a/xen/include/public/xen.h
> > +++ b/xen/include/public/xen.h
> > @@ -121,6 +121,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_ulong_t);
> > #define __HYPERVISOR_xc_reserved_op 39 /* reserved for XenClient
> */
> > #define __HYPERVISOR_xenpmu_op 40
> > #define __HYPERVISOR_dm_op 41
> > +#define __HYPERVISOR_domain_id 42 /* custom hypercall */
> >
> > /* Architecture-specific hypercall definitions. */
> > #define __HYPERVISOR_arch_0 48
> > diff --git a/xen/include/xen/hypercall.h b/xen/include/xen/hypercall.h
> > index cc99aea57d..438684df85 100644
> > --- a/xen/include/xen/hypercall.h
> > +++ b/xen/include/xen/hypercall.h
> > @@ -83,6 +83,11 @@ do_xen_version(
> > XEN_GUEST_HANDLE_PARAM(void) arg);
> >
> > extern long
> > +do_domain_id(
> > + int cmd,
> > + XEN_GUEST_HANDLE_PARAM(void) arg);
> > +
> > +extern long
> > do_console_io(
> > int cmd,
> > int count,
> > --
> > 2.11.0
> >
> >
> > From 3a896fcf3bc5d7f8c4613d9d4b854684ec981e7f Mon Sep 17 00:00:00 2001
> > From: Felix Schmoll <eggi.innovati...@gmail.com>
> > Date: Thu, 16 Mar 2017 22:38:23 +0100
> > Subject: [PATCH 2/2] Adjust libxc to new hypercall (untested)
> >
> > ---
> > tools/libxc/include/xenctrl.h | 1 +
> > tools/libxc/xc_private.c | 17 +++++++++++++++++
> > tools/libxc/xc_private.h | 8 ++++++++
> > 3 files changed, 26 insertions(+)
> >
> > diff --git a/tools/libxc/include/xenctrl.h
> b/tools/libxc/include/xenctrl.h
> > index a48981abea..e454b10f64 100644
> > --- a/tools/libxc/include/xenctrl.h
> > +++ b/tools/libxc/include/xenctrl.h
> > @@ -1546,6 +1546,7 @@ int xc_domctl(xc_interface *xch, struct xen_domctl
> > *domctl);
> > int xc_sysctl(xc_interface *xch, struct xen_sysctl *sysctl);
> >
> > int xc_version(xc_interface *xch, int cmd, void *arg);
> > +int xc_domid(xc_interface *xch, int cmd, void *arg);
> >
> > int xc_flask_op(xc_interface *xch, xen_flask_op_t *op);
> >
> > diff --git a/tools/libxc/xc_private.c b/tools/libxc/xc_private.c
> > index 72e6242417..f4f158c661 100644
> > --- a/tools/libxc/xc_private.c
> > +++ b/tools/libxc/xc_private.c
> > @@ -530,6 +530,23 @@ int xc_version(xc_interface *xch, int cmd, void
> *arg)
> > return rc;
> > }
> >
> > +int xc_domid(xc_interface *xch, int cmd, void *arg)
> > +{
> > + DECLARE_HYPERCALL_BOUNCE(arg, 0, XC_HYPERCALL_BUFFER_BOUNCE_OUT);
> /*
> > Size unknown until cmd decoded */
> > + size_t sz;
> > + int rc;
> > +
> > + /* TODO: might want to either consider or remove cmd param */
> > + sz = 0;
> > +
> > + HYPERCALL_BOUNCE_SET_SIZE(arg, sz);
> > +
> > + rc = do_domain_id(xch, cmd, HYPERCALL_BUFFER(arg));
>
> Most likely you will get rc = 0 because you're running your test program
> in Dom0. Try running this a DomU?
>
> > +
> > + return rc;
> > +}
> > +
> > +
> > unsigned long xc_make_page_below_4G(
> > xc_interface *xch, uint32_t domid, unsigned long mfn)
> > {
> > diff --git a/tools/libxc/xc_private.h b/tools/libxc/xc_private.h
> > index 1c27b0fded..7cf875ffb5 100644
> > --- a/tools/libxc/xc_private.h
> > +++ b/tools/libxc/xc_private.h
> > @@ -229,6 +229,14 @@ static inline int do_xen_version(xc_interface *xch,
> > int cmd, xc_hypercall_buffer
> > cmd, HYPERCALL_BUFFER_AS_ARG(dest));
> > }
> >
> > +/* custom hypercall */
> > +static inline int do_domain_id(xc_interface *xch, int cmd,
> > xc_hypercall_buffer_t *dest)
> > +{
> > + DECLARE_HYPERCALL_BUFFER_ARGUMENT(dest);
> > + return xencall2(xch->xcall, __HYPERVISOR_domain_id,
> > + cmd, HYPERCALL_BUFFER_AS_ARG(dest));
> > +}
> > +
> > static inline int do_physdev_op(xc_interface *xch, int cmd, void *op,
> > size_t len)
> > {
> > int ret = -1;
> > --
> > 2.11.0
> >
> > Now the question is how do I debug the hypercall. I compared what I have
> to
> > xen_version and to the patch for the last implemented hypercall but you
> > seem to have slightly changed the entry into to hypervisor since then. I
> > could use gdb for debugging the libxc-part, and printk is fine for the
> > kernel, but can you either point me to some discussion of the call-chain
> or
> > to some sort of debugger.
> >
>
> You can't attach a debugger to hypervisor. You can use printk in
> hypervisor to debug.
>
> Hypercall is just like syscall. You cross the boundary of different
> privilege levels. You've already identified the C entry point
> (x86/hypercall.c). For the ASM entry point, the PV one is in
> arch/x86/x86_64/entry.S and the HVM one is in arch/x86/hvm/vmx/vmx.c
> (Intel CPU) and arch/x86/svm/svm.c (AMD CPU). I don't think you need to
> care about the ASM entry points though.
>
> Please always develop against xen.git staging branch.
>
> I don't follow why your code doesn't work for you. Can you be more
> specific?
>
It returns -1 when I run the following program:
#include <stdio.h>
#include <xenctrl.h>
int main(void) {
xc_interface *xch = xc_interface_open(NULL, NULL, 0);
int ver = xc_version(xch, XENVER_version, NULL);
printf("Xen Version %d.%d\n", ver >> 16, ver & 0xffff);
int domid = xc_domid(xch, 0, NULL);
printf("Xen domain: %d\n", domid);
xc_interface_close(xch);
return 0;
}
Wei.
>
> > Any comments greatly appreciated.
> >
> > Felix
>
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