Re: [PATCH v2 3/3] tools/lixenguest: hide struct elf_dom_parms layout from users

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi Juergen,

> On 25 Sep 2020, at 07:20, Juergen Gross <jgross@xxxxxxxx> wrote:
> 
> Don't include struct elf_dom_parms in struct xc_dom_image, but rather
> use a pointer to reference it. Together with adding accessor functions
> for the externally needed elements this enables to drop including the
> Xen private header xen/libelf/libelf.h from xenguest.h.

There are several places in xg_dom_elfloader.c, xg_dom_arm.c and
xg_dom_armzimageloader.c which would need to be fixed as they are
using dom->parms.

Cheers
Bertrand

> 
> Fixes: 7e0165c19387 ("tools/libxc: untangle libxenctrl from libxenguest")
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
> stubdom/grub/kexec.c                | 18 +++---
> tools/libs/guest/include/xenguest.h | 29 +++-------
> tools/libs/guest/xg_dom_core.c      | 85 +++++++++++++++++++++++------
> tools/libs/guest/xg_private.h       |  1 +
> tools/libxl/libxl_x86_acpi.c        |  5 +-
> 5 files changed, 88 insertions(+), 50 deletions(-)
> 
> diff --git a/stubdom/grub/kexec.c b/stubdom/grub/kexec.c
> index e9a69d2a32..3da80b5b4a 100644
> --- a/stubdom/grub/kexec.c
> +++ b/stubdom/grub/kexec.c
> @@ -222,6 +222,7 @@ void kexec(void *kernel, long kernel_size, void *module, 
> long module_size, char
>     char features[] = "";
>     struct mmu_update *m2p_updates;
>     unsigned long nr_m2p_updates;
> +    uint64_t virt_base;
> 
>     DEBUG("booting with cmdline %s\n", cmdline);
>     xc_handle = xc_interface_open(0,0,0);
> @@ -294,10 +295,11 @@ void kexec(void *kernel, long kernel_size, void 
> *module, long module_size, char
>         goto out;
>     }
> 
> +    virt_base = xc_dom_virt_base(dom);
>     /* copy hypercall page */
>     /* TODO: domctl instead, but requires privileges */
> -    if (dom->parms.virt_hypercall != -1) {
> -        pfn = PHYS_PFN(dom->parms.virt_hypercall - dom->parms.virt_base);
> +    if (xc_dom_virt_hypercall(dom) != -1) {
> +        pfn = PHYS_PFN(xc_dom_virt_hypercall(dom) - virt_base);
>         memcpy((void *) pages[pfn], hypercall_page, PAGE_SIZE);
>     }
> 
> @@ -313,11 +315,11 @@ void kexec(void *kernel, long kernel_size, void 
> *module, long module_size, char
>     /* Move current console, xenstore and boot MFNs to the allocated place */
>     do_exchange(dom, dom->console_pfn, start_info.console.domU.mfn);
>     do_exchange(dom, dom->xenstore_pfn, start_info.store_mfn);
> -    DEBUG("virt base at %llx\n", dom->parms.virt_base);
> +    DEBUG("virt base at %llx\n", virt_base);
>     DEBUG("bootstack_pfn %lx\n", dom->bootstack_pfn);
> -    _boot_target = dom->parms.virt_base + PFN_PHYS(dom->bootstack_pfn);
> +    _boot_target = virt_base + PFN_PHYS(dom->bootstack_pfn);
>     DEBUG("_boot_target %lx\n", _boot_target);
> -    do_exchange(dom, PHYS_PFN(_boot_target - dom->parms.virt_base),
> +    do_exchange(dom, PHYS_PFN(_boot_target - virt_base),
>             virt_to_mfn(&_boot_page));
> 
>     if ( dom->arch_hooks->setup_pgtables )
> @@ -373,13 +375,13 @@ void kexec(void *kernel, long kernel_size, void 
> *module, long module_size, char
>     _boot_oldpdmfn = virt_to_mfn(start_info.pt_base);
>     DEBUG("boot old pd mfn %lx\n", _boot_oldpdmfn);
>     DEBUG("boot pd virt %lx\n", dom->pgtables_seg.vstart);
> -    _boot_pdmfn = dom->pv_p2m[PHYS_PFN(dom->pgtables_seg.vstart - 
> dom->parms.virt_base)];
> +    _boot_pdmfn = dom->pv_p2m[PHYS_PFN(dom->pgtables_seg.vstart - 
> virt_base)];
>     DEBUG("boot pd mfn %lx\n", _boot_pdmfn);
>     _boot_stack = _boot_target + PAGE_SIZE;
>     DEBUG("boot stack %lx\n", _boot_stack);
> -    _boot_start_info = dom->parms.virt_base + PFN_PHYS(dom->start_info_pfn);
> +    _boot_start_info = virt_base + PFN_PHYS(dom->start_info_pfn);
>     DEBUG("boot start info %lx\n", _boot_start_info);
> -    _boot_start = dom->parms.virt_entry;
> +    _boot_start = xc_dom_virt_entry(dom);
>     DEBUG("boot start %lx\n", _boot_start);
> 
>     /* Keep only useful entries */
> diff --git a/tools/libs/guest/include/xenguest.h 
> b/tools/libs/guest/include/xenguest.h
> index dba6a21643..a9984dbea5 100644
> --- a/tools/libs/guest/include/xenguest.h
> +++ b/tools/libs/guest/include/xenguest.h
> @@ -22,8 +22,6 @@
> #ifndef XENGUEST_H
> #define XENGUEST_H
> 
> -#include <xen/libelf/libelf.h>
> -
> #define XC_NUMA_NO_NODE   (~0U)
> 
> #define XCFLAGS_LIVE      (1 << 0)
> @@ -109,7 +107,7 @@ struct xc_dom_image {
>     uint32_t f_requested[XENFEAT_NR_SUBMAPS];
> 
>     /* info from (elf) kernel image */
> -    struct elf_dom_parms parms;
> +    struct elf_dom_parms *parms;
>     char *guest_type;
> 
>     /* memory layout */
> @@ -390,6 +388,13 @@ void *xc_dom_pfn_to_ptr_retcount(struct xc_dom_image 
> *dom, xen_pfn_t first,
>                                  xen_pfn_t count, xen_pfn_t *count_out);
> void xc_dom_unmap_one(struct xc_dom_image *dom, xen_pfn_t pfn);
> void xc_dom_unmap_all(struct xc_dom_image *dom);
> +void *xc_dom_vaddr_to_ptr(struct xc_dom_image *dom,
> +                          xen_vaddr_t vaddr, size_t *safe_region_out);
> +uint64_t xc_dom_virt_base(struct xc_dom_image *dom);
> +uint64_t xc_dom_virt_entry(struct xc_dom_image *dom);
> +uint64_t xc_dom_virt_hypercall(struct xc_dom_image *dom);
> +char *xc_dom_guest_os(struct xc_dom_image *dom);
> +bool xc_dom_feature_get(struct xc_dom_image *dom, unsigned int nr);
> 
> static inline void *xc_dom_seg_to_ptr_pages(struct xc_dom_image *dom,
>                                       struct xc_dom_seg *seg,
> @@ -411,24 +416,6 @@ static inline void *xc_dom_seg_to_ptr(struct 
> xc_dom_image *dom,
>     return xc_dom_seg_to_ptr_pages(dom, seg, &dummy);
> }
> 
> -static inline void *xc_dom_vaddr_to_ptr(struct xc_dom_image *dom,
> -                                        xen_vaddr_t vaddr,
> -                                        size_t *safe_region_out)
> -{
> -    unsigned int page_size = XC_DOM_PAGE_SIZE(dom);
> -    xen_pfn_t page = (vaddr - dom->parms.virt_base) / page_size;
> -    unsigned int offset = (vaddr - dom->parms.virt_base) % page_size;
> -    xen_pfn_t safe_region_count;
> -    void *ptr;
> -
> -    *safe_region_out = 0;
> -    ptr = xc_dom_pfn_to_ptr_retcount(dom, page, 0, &safe_region_count);
> -    if ( ptr == NULL )
> -        return ptr;
> -    *safe_region_out = (safe_region_count << XC_DOM_PAGE_SHIFT(dom)) - 
> offset;
> -    return ptr + offset;
> -}
> -
> static inline xen_pfn_t xc_dom_p2m(struct xc_dom_image *dom, xen_pfn_t pfn)
> {
>     if ( xc_dom_translated(dom) )
> diff --git a/tools/libs/guest/xg_dom_core.c b/tools/libs/guest/xg_dom_core.c
> index c0d4a0aa2f..f846d8e1ed 100644
> --- a/tools/libs/guest/xg_dom_core.c
> +++ b/tools/libs/guest/xg_dom_core.c
> @@ -735,6 +735,7 @@ void xc_dom_release(struct xc_dom_image *dom)
>         xc_dom_unmap_all(dom);
>     xc_dom_free_all(dom);
>     free(dom->arch_private);
> +    free(dom->parms);
>     free(dom);
> }
> 
> @@ -753,6 +754,12 @@ struct xc_dom_image *xc_dom_allocate(xc_interface *xch,
>     memset(dom, 0, sizeof(*dom));
>     dom->xch = xch;
> 
> +    dom->parms = malloc(sizeof(*dom->parms));
> +    if (!dom->parms)
> +        goto err;
> +    memset(dom->parms, 0, sizeof(*dom->parms));
> +    dom->alloc_malloc += sizeof(*dom->parms);
> +
>     dom->max_kernel_size = XC_DOM_DECOMPRESS_MAX;
>     dom->max_module_size = XC_DOM_DECOMPRESS_MAX;
>     dom->max_devicetree_size = XC_DOM_DECOMPRESS_MAX;
> @@ -762,12 +769,12 @@ struct xc_dom_image *xc_dom_allocate(xc_interface *xch,
>     if ( features )
>         elf_xen_parse_features(features, dom->f_requested, NULL);
> 
> -    dom->parms.virt_base = UNSET_ADDR;
> -    dom->parms.virt_entry = UNSET_ADDR;
> -    dom->parms.virt_hypercall = UNSET_ADDR;
> -    dom->parms.virt_hv_start_low = UNSET_ADDR;
> -    dom->parms.elf_paddr_offset = UNSET_ADDR;
> -    dom->parms.p2m_base = UNSET_ADDR;
> +    dom->parms->virt_base = UNSET_ADDR;
> +    dom->parms->virt_entry = UNSET_ADDR;
> +    dom->parms->virt_hypercall = UNSET_ADDR;
> +    dom->parms->virt_hv_start_low = UNSET_ADDR;
> +    dom->parms->elf_paddr_offset = UNSET_ADDR;
> +    dom->parms->p2m_base = UNSET_ADDR;
> 
>     dom->flags = SIF_VIRT_P2M_4TOOLS;
> 
> @@ -920,8 +927,8 @@ int xc_dom_parse_image(struct xc_dom_image *dom)
>     for ( i = 0; i < XENFEAT_NR_SUBMAPS; i++ )
>     {
>         dom->f_active[i] |= dom->f_requested[i]; /* cmd line */
> -        dom->f_active[i] |= dom->parms.f_required[i]; /* kernel   */
> -        if ( (dom->f_active[i] & dom->parms.f_supported[i]) !=
> +        dom->f_active[i] |= dom->parms->f_required[i]; /* kernel   */
> +        if ( (dom->f_active[i] & dom->parms->f_supported[i]) !=
>              dom->f_active[i] )
>         {
>             xc_dom_panic(dom->xch, XC_INVALID_PARAM,
> @@ -1142,8 +1149,8 @@ int xc_dom_build_image(struct xc_dom_image *dom)
>         goto err;
>     }
>     page_size = XC_DOM_PAGE_SIZE(dom);
> -    if ( dom->parms.virt_base != UNSET_ADDR )
> -        dom->virt_alloc_end = dom->parms.virt_base;
> +    if ( dom->parms->virt_base != UNSET_ADDR )
> +        dom->virt_alloc_end = dom->parms->virt_base;
> 
>     /* load kernel */
>     if ( xc_dom_alloc_segment(dom, &dom->kernel_seg, "kernel",
> @@ -1157,7 +1164,7 @@ int xc_dom_build_image(struct xc_dom_image *dom)
>     /* Don't load ramdisk / other modules now if no initial mapping required. 
> */
>     for ( mod = 0; mod < dom->num_modules; mod++ )
>     {
> -        unmapped_initrd = (dom->parms.unmapped_initrd &&
> +        unmapped_initrd = (dom->parms->unmapped_initrd &&
>                            !dom->modules[mod].seg.vstart);
> 
>         if ( dom->modules[mod].blob && !unmapped_initrd )
> @@ -1199,10 +1206,10 @@ int xc_dom_build_image(struct xc_dom_image *dom)
> 
>     /* allocate other pages */
>     if ( !dom->arch_hooks->p2m_base_supported ||
> -         dom->parms.p2m_base >= dom->parms.virt_base ||
> -         (dom->parms.p2m_base & (XC_DOM_PAGE_SIZE(dom) - 1)) )
> -        dom->parms.p2m_base = UNSET_ADDR;
> -    if ( dom->arch_hooks->alloc_p2m_list && dom->parms.p2m_base == 
> UNSET_ADDR &&
> +         dom->parms->p2m_base >= dom->parms->virt_base ||
> +         (dom->parms->p2m_base & (XC_DOM_PAGE_SIZE(dom) - 1)) )
> +        dom->parms->p2m_base = UNSET_ADDR;
> +    if ( dom->arch_hooks->alloc_p2m_list && dom->parms->p2m_base == 
> UNSET_ADDR &&
>          dom->arch_hooks->alloc_p2m_list(dom) != 0 )
>         goto err;
>     if ( dom->arch_hooks->alloc_magic_pages(dom) != 0 )
> @@ -1228,7 +1235,7 @@ int xc_dom_build_image(struct xc_dom_image *dom)
> 
>     for ( mod = 0; mod < dom->num_modules; mod++ )
>     {
> -        unmapped_initrd = (dom->parms.unmapped_initrd &&
> +        unmapped_initrd = (dom->parms->unmapped_initrd &&
>                            !dom->modules[mod].seg.vstart);
> 
>         /* Load ramdisk / other modules if no initial mapping required. */
> @@ -1247,11 +1254,11 @@ int xc_dom_build_image(struct xc_dom_image *dom)
>     }
> 
>     /* Allocate p2m list if outside of initial kernel mapping. */
> -    if ( dom->arch_hooks->alloc_p2m_list && dom->parms.p2m_base != 
> UNSET_ADDR )
> +    if ( dom->arch_hooks->alloc_p2m_list && dom->parms->p2m_base != 
> UNSET_ADDR )
>     {
>         if ( dom->arch_hooks->alloc_p2m_list(dom) != 0 )
>             goto err;
> -        dom->p2m_seg.vstart = dom->parms.p2m_base;
> +        dom->p2m_seg.vstart = dom->parms->p2m_base;
>     }
> 
>     return 0;
> @@ -1260,6 +1267,48 @@ int xc_dom_build_image(struct xc_dom_image *dom)
>     return -1;
> }
> 
> +void *xc_dom_vaddr_to_ptr(struct xc_dom_image *dom,
> +                          xen_vaddr_t vaddr, size_t *safe_region_out)
> +{
> +    unsigned int page_size = XC_DOM_PAGE_SIZE(dom);
> +    xen_pfn_t page = (vaddr - dom->parms->virt_base) / page_size;
> +    unsigned int offset = (vaddr - dom->parms->virt_base) % page_size;
> +    xen_pfn_t safe_region_count;
> +    void *ptr;
> +
> +    *safe_region_out = 0;
> +    ptr = xc_dom_pfn_to_ptr_retcount(dom, page, 0, &safe_region_count);
> +    if ( ptr == NULL )
> +        return ptr;
> +    *safe_region_out = (safe_region_count << XC_DOM_PAGE_SHIFT(dom)) - 
> offset;
> +    return ptr + offset;
> +}
> +
> +uint64_t xc_dom_virt_base(struct xc_dom_image *dom)
> +{
> +    return dom->parms->virt_base;
> +}
> +
> +uint64_t xc_dom_virt_entry(struct xc_dom_image *dom)
> +{
> +    return dom->parms->virt_entry;
> +}
> +
> +uint64_t xc_dom_virt_hypercall(struct xc_dom_image *dom)
> +{
> +    return dom->parms->virt_hypercall;
> +}
> +
> +char *xc_dom_guest_os(struct xc_dom_image *dom)
> +{
> +    return dom->parms->guest_os;
> +}
> +
> +bool xc_dom_feature_get(struct xc_dom_image *dom, unsigned int nr)
> +{
> +    return elf_xen_feature_get(nr, dom->parms->f_supported);
> +}
> +
> /*
>  * Local variables:
>  * mode: C
> diff --git a/tools/libs/guest/xg_private.h b/tools/libs/guest/xg_private.h
> index 9940d554ef..fee3191cd4 100644
> --- a/tools/libs/guest/xg_private.h
> +++ b/tools/libs/guest/xg_private.h
> @@ -31,6 +31,7 @@
> 
> #include <xen/memory.h>
> #include <xen/elfnote.h>
> +#include <xen/libelf/libelf.h>
> 
> #ifndef ELFSIZE
> #include <limits.h>
> diff --git a/tools/libxl/libxl_x86_acpi.c b/tools/libxl/libxl_x86_acpi.c
> index 1a4e9e98de..3eca1c7a9f 100644
> --- a/tools/libxl/libxl_x86_acpi.c
> +++ b/tools/libxl/libxl_x86_acpi.c
> @@ -220,9 +220,8 @@ int libxl__dom_load_acpi(libxl__gc *gc,
>      * and so we need to put RSDP in location that can be discovered by ACPI's
>      * standard search method, in R-O BIOS memory (we chose last 64 bytes)
>      */
> -    if (strcmp(dom->parms.guest_os, "linux") ||
> -        elf_xen_feature_get(XENFEAT_linux_rsdp_unrestricted,
> -                            dom->parms.f_supported))
> +    if (strcmp(xc_dom_guest_os(dom), "linux") ||
> +        xc_dom_feature_get(dom, XENFEAT_linux_rsdp_unrestricted))
>         dom->acpi_modules[0].guest_addr_out = ACPI_INFO_PHYSICAL_ADDRESS +
>             (1 + acpi_pages_num) * libxl_ctxt.page_size;
>     else
> -- 
> 2.26.2
> 
>