Ah, this is because you poll the ring and never actually use let alone clear
the event channel rx port? This looks like a good fix, thanks.
-- Keir
On 20/07/2010 11:38, "Tim Deegan" <Tim.Deegan@xxxxxxxxxxxxx> wrote:
> Here's another patch that also unsticks CentOS 5.5 boot for me, and
> seems safer and saner (even if it turns out that the bug is somewhere
> else and I'm just perturbing the inputs to some more complex system...)
>
> Cheers,
>
> Tim.
>
> hvmloader: clear the xenbus event-channel when we're done with it.
> Otherwise a later xenbus client that naively waits for the rising edge
> could get stuck.
>
> Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
>
> diff -r c4a83e3cc6b4 tools/firmware/hvmloader/util.c
> --- a/tools/firmware/hvmloader/util.c Thu Jul 15 18:18:16 2010 +0100
> +++ b/tools/firmware/hvmloader/util.c Tue Jul 20 11:34:06 2010 +0100
> @@ -587,10 +587,28 @@
> return table;
> }
>
> +struct shared_info *get_shared_info(void)
> +{
> + static struct shared_info *shared_info = NULL;
> + struct xen_add_to_physmap xatp;
> +
> + if ( shared_info == NULL )
> + {
> + /* Map shared-info page. */
> + xatp.domid = DOMID_SELF;
> + xatp.space = XENMAPSPACE_shared_info;
> + xatp.idx = 0;
> + xatp.gpfn = 0xfffff;
> + if ( hypercall_memory_op(XENMEM_add_to_physmap, &xatp) != 0 )
> + BUG();
> + shared_info = (struct shared_info *) (xatp.gpfn << 12);
> + }
> + return shared_info;
> +}
> +
> uint16_t get_cpu_mhz(void)
> {
> - struct xen_add_to_physmap xatp;
> - struct shared_info *shared_info = (struct shared_info *)0xfffff000;
> + struct shared_info *shared_info = get_shared_info();
> struct vcpu_time_info *info = &shared_info->vcpu_info[0].time;
> uint64_t cpu_khz;
> uint32_t tsc_to_nsec_mul, version;
> @@ -599,14 +617,6 @@
> static uint16_t cpu_mhz;
> if ( cpu_mhz != 0 )
> return cpu_mhz;
> -
> - /* Map shared-info page. */
> - xatp.domid = DOMID_SELF;
> - xatp.space = XENMAPSPACE_shared_info;
> - xatp.idx = 0;
> - xatp.gpfn = (unsigned long)shared_info >> 12;
> - if ( hypercall_memory_op(XENMEM_add_to_physmap, &xatp) != 0 )
> - BUG();
>
> /* Get a consistent snapshot of scale factor (multiplier and shift). */
> do {
> diff -r c4a83e3cc6b4 tools/firmware/hvmloader/util.h
> --- a/tools/firmware/hvmloader/util.h Thu Jul 15 18:18:16 2010 +0100
> +++ b/tools/firmware/hvmloader/util.h Tue Jul 20 11:34:06 2010 +0100
> @@ -68,6 +68,9 @@
> #define pci_writeb(devfn, reg, val) (pci_write(devfn, reg, 1, (uint8_t) val))
> #define pci_writew(devfn, reg, val) (pci_write(devfn, reg, 2, (uint16_t)val))
> #define pci_writel(devfn, reg, val) (pci_write(devfn, reg, 4, (uint32_t)val))
> +
> +/* Get a pointer to the shared-info page */
> +struct shared_info *get_shared_info(void);
>
> /* Get CPU speed in MHz. */
> uint16_t get_cpu_mhz(void);
> diff -r c4a83e3cc6b4 tools/firmware/hvmloader/xenbus.c
> --- a/tools/firmware/hvmloader/xenbus.c Thu Jul 15 18:18:16 2010 +0100
> +++ b/tools/firmware/hvmloader/xenbus.c Tue Jul 20 11:34:06 2010 +0100
> @@ -53,14 +53,20 @@
> (unsigned long) rings, (unsigned long) event);
> }
>
> -/* Reset the xenbus connection so the next kernel can start again.
> - * We zero out the whole ring -- the backend can handle this, and it's
> - * not going to surprise any frontends since it's equivalent to never
> - * having used the rings. */
> +/* Reset the xenbus connection so the next kernel can start again. */
> void xenbus_shutdown(void)
> {
> ASSERT(rings != NULL);
> +
> + /* We zero out the whole ring -- the backend can handle this, and it's
> + * not going to surprise any frontends since it's equivalent to never
> + * having used the rings. */
> memset(rings, 0, sizeof *rings);
> +
> + /* Clear the xenbus event-channel too */
> + get_shared_info()->evtchn_pending[event / sizeof (unsigned long)]
> + &= ~(1UL << ((event % sizeof (unsigned long))));
> +
> rings = NULL;
> }
>
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