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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4.2] libxc: Defer initialization of start_page for HVM guests
On 07/01/16 23:19, Boris Ostrovsky wrote:
> With commit 8c45adec18e0 ("libxc: create unmapped initrd in domain
> builder if supported") location of ramdisk may not be available to
> HVMlite guests by the time alloc_magic_pages_hvm() is invoked if the
> guest supports unmapped initrd.
>
> So let's move ramdisk info initialization (along with a few other
> operations that are not directly related to allocating magic/special
> pages) from alloc_magic_pages_hvm() to bootlate_hvm().
>
> Since we now split allocation and mapping of the start_info segment
> let's stash it, along with cmdline length, in xc_dom_image so that we
> can check whether we are mapping correctly-sized range.
>
> We can also stop using xc_dom_image.start_info_pfn and leave it for
> PV(H) guests only.
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> ---
> v4:
> * See the last two paragraphs from commit message above
>
> v4.1:
> * Inverted testing of start_info_size in bootlate_hvm().
>
> v4.2
> * <facepalm> Actually do what I said I'd do in 4.1
>
> tools/libxc/include/xc_dom.h | 2 +
> tools/libxc/xc_dom_x86.c | 140 +++++++++++++++++++++++------------------
> 2 files changed, 80 insertions(+), 62 deletions(-)
>
> diff --git a/tools/libxc/include/xc_dom.h b/tools/libxc/include/xc_dom.h
> index 2460818..cac4698 100644
> --- a/tools/libxc/include/xc_dom.h
> +++ b/tools/libxc/include/xc_dom.h
> @@ -71,6 +71,7 @@ struct xc_dom_image {
>
> /* arguments and parameters */
> char *cmdline;
> + size_t cmdline_size;
> uint32_t f_requested[XENFEAT_NR_SUBMAPS];
>
> /* info from (elf) kernel image */
> @@ -91,6 +92,7 @@ struct xc_dom_image {
> struct xc_dom_seg p2m_seg;
> struct xc_dom_seg pgtables_seg;
> struct xc_dom_seg devicetree_seg;
> + struct xc_dom_seg start_info_seg; /* HVMlite only */
Instead of adding HVM specific members here, you could make use of
dom.arch_private and use just a local structure defined in xc_dom_x86.c.
Juergen
> xen_pfn_t start_info_pfn;
> xen_pfn_t console_pfn;
> xen_pfn_t xenstore_pfn;
> diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
> index b8d2904..edf2db1 100644
> --- a/tools/libxc/xc_dom_x86.c
> +++ b/tools/libxc/xc_dom_x86.c
> @@ -586,23 +586,12 @@ static void build_hvm_info(void *hvm_info_page, struct
> xc_dom_image *dom)
> static int alloc_magic_pages_hvm(struct xc_dom_image *dom)
> {
> unsigned long i;
> - void *hvm_info_page;
> uint32_t *ident_pt, domid = dom->guest_domid;
> int rc;
> xen_pfn_t special_array[X86_HVM_NR_SPECIAL_PAGES];
> xen_pfn_t ioreq_server_array[NR_IOREQ_SERVER_PAGES];
> xc_interface *xch = dom->xch;
>
> - if ( dom->device_model )
> - {
> - if ( (hvm_info_page = xc_map_foreign_range(
> - xch, domid, PAGE_SIZE, PROT_READ | PROT_WRITE,
> - HVM_INFO_PFN)) == NULL )
> - goto error_out;
> - build_hvm_info(hvm_info_page, dom);
> - munmap(hvm_info_page, PAGE_SIZE);
> - }
> -
> /* Allocate and clear special pages. */
> for ( i = 0; i < X86_HVM_NR_SPECIAL_PAGES; i++ )
> special_array[i] = special_pfn(i);
> @@ -636,65 +625,25 @@ static int alloc_magic_pages_hvm(struct xc_dom_image
> *dom)
>
> if ( !dom->device_model )
> {
> - struct xc_dom_seg seg;
> - struct hvm_start_info *start_info;
> - char *cmdline;
> - struct hvm_modlist_entry *modlist;
> - void *start_page;
> - size_t cmdline_size = 0;
> - size_t start_info_size = sizeof(*start_info);
> + size_t start_info_size = sizeof(struct hvm_start_info);
>
> if ( dom->cmdline )
> {
> - cmdline_size = ROUNDUP(strlen(dom->cmdline) + 1, 8);
> - start_info_size += cmdline_size;
> -
> + dom->cmdline_size = ROUNDUP(strlen(dom->cmdline) + 1, 8);
> + start_info_size += dom->cmdline_size;
> }
> +
> + /* Limited to one module. */
> if ( dom->ramdisk_blob )
> - start_info_size += sizeof(*modlist); /* Limited to one module. */
> + start_info_size += sizeof(struct hvm_modlist_entry);
>
> - rc = xc_dom_alloc_segment(dom, &seg, "HVMlite start info", 0,
> - start_info_size);
> + rc = xc_dom_alloc_segment(dom, &dom->start_info_seg,
> + "HVMlite start info", 0, start_info_size);
> if ( rc != 0 )
> {
> DOMPRINTF("Unable to reserve memory for the start info");
> goto out;
> }
> -
> - start_page = xc_map_foreign_range(xch, domid, start_info_size,
> - PROT_READ | PROT_WRITE,
> - seg.pfn);
> - if ( start_page == NULL )
> - {
> - DOMPRINTF("Unable to map HVM start info page");
> - goto error_out;
> - }
> -
> - start_info = start_page;
> - cmdline = start_page + sizeof(*start_info);
> - modlist = start_page + sizeof(*start_info) + cmdline_size;
> -
> - if ( dom->cmdline )
> - {
> - strncpy(cmdline, dom->cmdline, cmdline_size);
> - start_info->cmdline_paddr = (seg.pfn << PAGE_SHIFT) +
> - ((uintptr_t)cmdline - (uintptr_t)start_info);
> - }
> -
> - if ( dom->ramdisk_blob )
> - {
> - modlist[0].paddr = dom->ramdisk_seg.vstart -
> dom->parms.virt_base;
> - modlist[0].size = dom->ramdisk_seg.vend -
> dom->ramdisk_seg.vstart;
> - start_info->modlist_paddr = (seg.pfn << PAGE_SHIFT) +
> - ((uintptr_t)modlist - (uintptr_t)start_info);
> - start_info->nr_modules = 1;
> - }
> -
> - start_info->magic = HVM_START_MAGIC_VALUE;
> -
> - munmap(start_page, start_info_size);
> -
> - dom->start_info_pfn = seg.pfn;
> }
> else
> {
> @@ -1095,8 +1044,8 @@ static int vcpu_hvm(struct xc_dom_image *dom)
> /* Set the IP. */
> bsp_ctx.cpu.rip = dom->parms.phys_entry;
>
> - if ( dom->start_info_pfn )
> - bsp_ctx.cpu.rbx = dom->start_info_pfn << PAGE_SHIFT;
> + if ( dom->start_info_seg.pfn )
> + bsp_ctx.cpu.rbx = dom->start_info_seg.pfn << PAGE_SHIFT;
>
> /* Set the end descriptor. */
> bsp_ctx.end_d.typecode = HVM_SAVE_CODE(END);
> @@ -1783,7 +1732,74 @@ static int alloc_pgtables_hvm(struct xc_dom_image *dom)
>
> static int bootlate_hvm(struct xc_dom_image *dom)
> {
> - DOMPRINTF("%s: doing nothing", __func__);
> + uint32_t domid = dom->guest_domid;
> + xc_interface *xch = dom->xch;
> +
> + if ( !dom->device_model )
> + {
> + struct hvm_start_info *start_info;
> + size_t start_info_size;
> + void *start_page;
> +
> + start_info_size = sizeof(*start_info) + dom->cmdline_size;
> + if ( dom->ramdisk_blob )
> + start_info_size += sizeof(struct hvm_modlist_entry);
> +
> + if ( start_info_size >
> + dom->start_info_seg.pages << XC_DOM_PAGE_SHIFT(dom) )
> + {
> + DOMPRINTF("Trying to map beyond start_info_seg");
> + return -1;
> + }
> +
> + start_page = xc_map_foreign_range(xch, domid, start_info_size,
> + PROT_READ | PROT_WRITE,
> + dom->start_info_seg.pfn);
> + if ( start_page == NULL )
> + {
> + DOMPRINTF("Unable to map HVM start info page");
> + return -1;
> + }
> +
> + start_info = start_page;
> +
> + if ( dom->cmdline )
> + {
> + char *cmdline = start_page + sizeof(*start_info);
> +
> + strncpy(cmdline, dom->cmdline, dom->cmdline_size);
> + start_info->cmdline_paddr = (dom->start_info_seg.pfn <<
> PAGE_SHIFT) +
> + ((uintptr_t)cmdline - (uintptr_t)start_info);
> + }
> +
> + if ( dom->ramdisk_blob )
> + {
> + struct hvm_modlist_entry *modlist =
> + start_page + sizeof(*start_info) + dom->cmdline_size;
> +
> + modlist[0].paddr = dom->ramdisk_seg.vstart -
> dom->parms.virt_base;
> + modlist[0].size = dom->ramdisk_seg.vend -
> dom->ramdisk_seg.vstart;
> + start_info->modlist_paddr = (dom->start_info_seg.pfn <<
> PAGE_SHIFT) +
> + ((uintptr_t)modlist - (uintptr_t)start_info);
> + start_info->nr_modules = 1;
> + }
> +
> + start_info->magic = HVM_START_MAGIC_VALUE;
> +
> + munmap(start_page, start_info_size);
> + }
> + else
> + {
> + void *hvm_info_page;
> +
> + if ( (hvm_info_page = xc_map_foreign_range(
> + xch, domid, PAGE_SIZE, PROT_READ | PROT_WRITE,
> + HVM_INFO_PFN)) == NULL )
> + return -1;
> + build_hvm_info(hvm_info_page, dom);
> + munmap(hvm_info_page, PAGE_SIZE);
> + }
> +
> return 0;
> }
>
>
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