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SubjectRe: [PATCH V10 01/14] xen/pvh: Support ParaVirtualized Hardware extensions.
On Fri, Dec 13, 2013 at 10:44:31AM +0000, David Vrabel wrote:
> On 13/12/13 02:10, Konrad Rzeszutek Wilk wrote:
> > From: Mukesh Rathor <mukesh.rathor@oracle.com>
> >
> > PVH allows PV linux guest to utilize hardware extended capabilities, such
> > as running MMU updates in a HVM container.
> >
> > This patch allows it to be configured and enabled. Also, basic header file
> > changes to add new subcalls to physmap hypercall.
> >
> > Lastly, mfn_to_local_pfn must return mfn for paging mode translate
> > (since we let the hypervisor - or CPU - do them for us).
> [...]
> > --- a/arch/x86/include/asm/xen/page.h
> > +++ b/arch/x86/include/asm/xen/page.h
> > @@ -168,6 +168,9 @@ static inline xpaddr_t machine_to_phys(xmaddr_t machine)
> > static inline unsigned long mfn_to_local_pfn(unsigned long mfn)
> > {
> > unsigned long pfn = mfn_to_pfn(mfn);
> > +
> > + if (xen_feature(XENFEAT_auto_translated_physmap))
> > + return mfn;
>
> This does the mfn_to_pfn() call first and then ignores the result.
>
> > if (get_phys_to_machine(pfn) != mfn)
> > return -1; /* force !pfn_valid() */
> > return pfn;
> > diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
> > index 1a3c765..4d890c3 100644
> > --- a/arch/x86/xen/Kconfig
> > +++ b/arch/x86/xen/Kconfig
> > @@ -51,3 +51,13 @@ config XEN_DEBUG_FS
> > Enable statistics output and various tuning options in debugfs.
> > Enabling this option may incur a significant performance overhead.
> >
> > +config XEN_X86_PVH
> > + bool "Support for running as a PVH guest (EXPERIMENTAL)"
> > + depends on X86_64 && XEN && EXPERIMENTAL
>
> Drop EXPERIMENTAL here (not in the follow up patch).
>
> > + default n
>
> default y or don't provide this as a user selectable choice.
>
> > diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
> > index 7faed58..1a6bca1 100644
> > --- a/arch/x86/xen/xen-head.S
> > +++ b/arch/x86/xen/xen-head.S
> > @@ -13,6 +13,15 @@
> > #include <xen/interface/elfnote.h>
> > #include <asm/xen/interface.h>
> >
> > +#ifdef CONFIG_XEN_X86_PVH
> > +#define FEATURES_PVH "|writable_descriptor_tables" \
> > + "|auto_translated_physmap" \
> > + "|supervisor_mode_kernel" \
> > + "|hvm_callback_vector"
> > +#else
> > +#define FEATURES_PVH /* Not supported */
> > +#endif
> > +
> > __INIT
> > ENTRY(startup_xen)
> > cld
> > @@ -95,7 +104,7 @@ NEXT_HYPERCALL(arch_6)
> > #endif
> > ELFNOTE(Xen, XEN_ELFNOTE_ENTRY, _ASM_PTR startup_xen)
> > ELFNOTE(Xen, XEN_ELFNOTE_HYPERCALL_PAGE, _ASM_PTR hypercall_page)
> > - ELFNOTE(Xen, XEN_ELFNOTE_FEATURES, .asciz "!writable_page_tables|pae_pgdir_above_4gb")
> > + ELFNOTE(Xen, XEN_ELFNOTE_FEATURES, .asciz "!writable_page_tables|pae_pgdir_above_4gb"FEATURES_PVH)
> > ELFNOTE(Xen, XEN_ELFNOTE_PAE_MODE, .asciz "yes")
> > ELFNOTE(Xen, XEN_ELFNOTE_LOADER, .asciz "generic")
> > ELFNOTE(Xen, XEN_ELFNOTE_L1_MFN_VALID,
>
> Not clear how this can be part of the first patch. A guest with only
> this patch cannot actually work in PVH mode, right?

Good point. We should make this one of the last patches or split
this part out.

>
> > diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h
> > index 2ecfe4f..a122164 100644
> > --- a/include/xen/interface/memory.h
> > +++ b/include/xen/interface/memory.h
> > @@ -175,7 +175,10 @@ struct xen_add_to_physmap {
> > uint16_t size;
> >
> > /* Source mapping space. */
> > - unsigned int space;
> > + uint16_t space;
> > + domid_t foreign_domid; /* IFF XENMAPSPACE_gmfn_foreign */
> > +
> > +#define XENMAPIDX_grant_table_status 0x80000000
>
> What's this change? It doesn't match the hypervisor.
>
> > --- a/include/xen/interface/physdev.h
> > +++ b/include/xen/interface/physdev.h
> > @@ -291,6 +291,16 @@ struct physdev_dbgp_op {
> > } u;
> > };
> >
> > +#define PHYSDEVOP_map_iomem 30
> > +struct physdev_map_iomem {
> > + /* IN */
> > + uint64_t first_gfn;
> > + uint64_t first_mfn;
> > + uint32_t nr_mfns;
> > + uint32_t add_mapping; /* 1 == add mapping; 0 == unmap */
> > +
> > +};
> > +
>
> Not provided by the hypervisor.

Mukesh, could you send a followup patch to the entire patchset which
fixes the change so I can make sure to have the right hypervisor ABI please?


>
> David


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