Re: [PATCH v7 12/32] xen/x86: add bitmap of enabled emulated devices

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 10/02/2015 11:48 AM, Roger Pau Monne wrote:
> Introduce a bitmap in x86 xen_arch_domainconfig that allows enabling or
> disabling specific devices emulated inside of Xen for HVM guests.
>

...

> diff --git a/xen/include/public/arch-x86/xen.h b/xen/include/public/arch-x86/xen.h
> index 2ecc9c9..c97a9b4 100644
> --- a/xen/include/public/arch-x86/xen.h
> +++ b/xen/include/public/arch-x86/xen.h
> @@ -268,7 +268,28 @@ typedef struct arch_shared_info arch_shared_info_t;
>    * XEN_DOMCTL_INTERFACE_VERSION.
>    */
>   struct xen_arch_domainconfig {
> -    char dummy;
> +#define _XEN_X86_EMU_LAPIC          0
> +#define XEN_X86_EMU_LAPIC           (1U<<_XEN_X86_EMU_LAPIC)
> +#define _XEN_X86_EMU_HPET           1
> +#define XEN_X86_EMU_HPET            (1U<<_XEN_X86_EMU_HPET)
> +#define _XEN_X86_EMU_PMTIMER        2
> +#define XEN_X86_EMU_PMTIMER         (1U<<_XEN_X86_EMU_PMTIMER)
> +#define _XEN_X86_EMU_RTC            3
> +#define XEN_X86_EMU_RTC             (1U<<_XEN_X86_EMU_RTC)
> +#define _XEN_X86_EMU_IOAPIC         4
> +#define XEN_X86_EMU_IOAPIC          (1U<<_XEN_X86_EMU_IOAPIC)
> +#define _XEN_X86_EMU_PIC            5
> +#define XEN_X86_EMU_PIC             (1U<<_XEN_X86_EMU_PIC)
> +#define _XEN_X86_EMU_VGA            6
> +#define XEN_X86_EMU_VGA             (1U<<_XEN_X86_EMU_VGA)
> +#define _XEN_X86_EMU_IOMMU          7
> +#define XEN_X86_EMU_IOMMU           (1U<<_XEN_X86_EMU_IOMMU)

What about PIT? Should we (initially) disable it as well?

I (by mistake) enabled it in my guest and crashed the hypervisor due to 
unprotected access to vlapic in pt_update_irq(). I started fixing it but 
then realized that perhaps we shouldn't have PIT at all. Which did solve 
my problems.

(Regardless of whether we have PIT we should probably guard 
vlapic_accept_pit_interrupt() in pit_irq_masked() with has_vlapic())

-boris

> +
> +#define XEN_X86_EMU_ALL             (XEN_X86_EMU_LAPIC | XEN_X86_EMU_HPET |  \
> +                                     XEN_X86_EMU_PMTIMER | XEN_X86_EMU_RTC | \
> +                                     XEN_X86_EMU_IOAPIC | XEN_X86_EMU_PIC |  \
> +                                     XEN_X86_EMU_VGA | XEN_X86_EMU_IOMMU)
> +    uint32_t emulation_flags;
>   };
>   #endif
>