Re: HVM hypercalls

[veeruyours <veeruyours@gmail.com>]

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I am running 2.6.30 (downloaded from kernel.org) on top of CENTOS 5.4.
Do u mean i should enable following option

--> Processor type and features
      [*] Paravirtualized guest support  --->
             --> [ ]   Xen guest support (NEW)

But enabling this also selects PARAVIRT and does it make my guest PV guest
or PVHVM guest?

--- Paravirtualized guest support
[*]   Xen guest support
(32)    Maximum allowed size of a domain in gigabytes (NEW)
[ ]     Enable Xen debug and tuning parameters in debugfs
[ ]   KVM paravirtualized clock (NEW)
[ ]   KVM Guest support (NEW)
-*-   Enable paravirtualization code
[ ]     Paravirtualization layer for spinlocks

Could you please suggest how to enable only PVHVM support? I am fine for
moving to recent kernels if required.

Thanks & Regards,
VSR.

On Tue, May 24, 2011 at 5:38 PM, Ian Campbell-12 [via Xen] <
ml-node+4421864-1644938153-207502@n5.nabble.com> wrote:

> On Mon, 2011-05-23 at 14:52 +0100, veerasena reddy wrote:
>
> > Hi,
> >
> > Thanks a lot for quick reply.
> >
> > I modified my code to get physical page address and now i do not see
> > error message on XEN hypervisor.
> > Could you please correct if am writing proper physical address or not?
> >
> > We can write the page address to hypervisor using wrmsr() but who
> > should set hypercall_page which is declared as extern in hypercall.h
> > on HVM? Because when i try to invoke HYPERCALL_xxxx(), it reported
> > hypercall_page not declared. Do we need to enable CONFIG_XEN in HVM
> > kernel in order to invoke hypercalls to hypervisor?
>
> Which kernel are you running with?
>
> This should all be taken care of for you in a kernel with PVHVM support
> enabled.
>
> > Could you please share any sample code if you have to get a clear
> > understanding of HVM hypercalls.
> >
> > {
> >         char id[13];
> >         unsigned int msr1;
> >         unsigned long  my_hpage_phys;
> >         int my_hpage_lo, my_hpage_hi;
> >
> >         __asm__ __volatile__(
> >                 "cpuid"
> >                 : "=b" (*(int *)(&id[0])),
> >                   "=d" (*(int *)(&id[8])),
> >                   "=c" (*(int *)(&id[4]))
> >                 : "a" (0x40000000)
> >         );
> >         id[12]='\0';
> >         printk("CPU ID read- %s\n", id);
> >
> >         /* Read MSR register */
> >         __asm__ __volatile__(
> >                 "cpuid"
> >                 : "=b" (*(int *)(&msr1))
> >                 : "a" (0x40000002)
> >         );
> >
> >         my_hpage_phys = __get_free_page(GFP_ATOMIC);
> >         hypercall_page = virt_to_phys(my_hpage_phys);
> >         printk("my_hpage_phys get_free = %lx\n", my_hpage_phys);
> >         printk("hypercal_page = %p\n", hypercall_page);
> >
> >         my_hpage_lo = (unsigned long)hypercall_page & 0xffffffff;
> >         my_hpage_hi = (unsigned long)hypercall_page >> 32;
> >         printk("my_hpage lo = %x hi = %x\n", my_hpage_lo,
> > my_hpage_hi);
> >         /* Write hypercall page address to MSR */
> >         wrmsr(msr1, my_hpage_lo, my_hpage_hi);
> >
> >         return 0;
> > }
> >
> > ================= output on HVM ==========
> > [root@localhost src]# dmesg
> > my_hypercall_page @ ffffffffa0388000
> > CPU ID read- XenVMMXenVMM
> > my_hpage_phys get_free = ffff880005c0b000
> > hypercal_page = 0000000005c0b000
> > my_hpage lo = 5c0b000 hi = 0
> > ============================
> >
> > Thanks & Regards,
> > VSR.
> >
> > On Mon, May 23, 2011 at 1:52 PM, Ian Campbell
> > <[hidden email] <http://user/SendEmail.jtp?type=node&node=4421864&i=0>>
> wrote:
> >         On Mon, 2011-05-23 at 08:48 +0100, veeruyours wrote:
> >         > Hi,
> >         >
> >         > I recently started working on XEN, and I am looking for ways
> >         to invoke
> >         > hypercalls from HVM.
> >         > I followed your instructions and succeeded in reading MSR
> >         register.
> >         > But when i attempt to write the physical address of a 4K
> >         page from my HVM
> >         > guest (2.6.30 kernel), i observed the XEN hypervisor
> >         reporting it as bad
> >         > GMFN as follows.
> >         >
> >         > [root@f13 ~]# xm dmesg -c
> >         > (XEN) traps.c:664:d17 Bad GMFN ffff88001e925 (MFN
> >         ffffffffffffffff) to MSR
> >         > 40000000
> >
> >
> >         That supposed GMFN (fff88001e925) looks an awful lot like a
> >         virtual
> >         address and not a physical one to me, unless your guest really
> >         has >4TB
> >         of RAM assigned...
> >
> >
> >         >
> >         > Could you please help me in understanding what went wrong in
> >         my
> >         > implementation.
> >         >
> >         > I am running XEN 4.0.1 on AMD 64bit machine with svm support
> >         and the dom0
> >         > kernel running 2.6.32.39.
> >         >
> >         > The
> >         > Thanks & Regards,
> >         > VSR.
> >         >
> >         >
> >         > --
> >         > View this message in context:
> >
> http://xen.1045712.n5.nabble.com/HVM-hypercalls-tp2541346p4418332.html
> >         > Sent from the Xen - Dev mailing list archive at Nabble.com.
> >         >
> >         > _______________________________________________
> >         > Xen-devel mailing list
> >         > [hidden email]<http://user/SendEmail.jtp?type=node&node=4421864&i=1>
> >         > http://lists.xensource.com/xen-devel
> >
> >
> >
> >
>
>
>
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