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Re: [PATCH v2 1/6] xen: factor out p2m list allocation into separate fun
From: |
Juergen Gross |
Subject: |
Re: [PATCH v2 1/6] xen: factor out p2m list allocation into separate function |
Date: |
Thu, 11 Feb 2016 13:38:10 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 |
On 11/02/16 13:19, Daniel Kiper wrote:
> On Thu, Feb 11, 2016 at 08:53:21AM +0100, Juergen Gross wrote:
>> Do the p2m list allocation of the to be loaded kernel in a separate
>> function. This will allow doing the p2m list allocation at different
>> times of the boot preparations depending on the features the kernel
>> is supporting.
>>
>> While at this remove superfluous setting of first_p2m_pfn and
>> nr_p2m_frames as those are needed only in case of the p2m list not
>> being mapped by the initial kernel mapping.
>>
>> Signed-off-by: Juergen Gross <address@hidden>
>> ---
>> grub-core/loader/i386/xen.c | 70
>> ++++++++++++++++++++++++++-------------------
>> 1 file changed, 40 insertions(+), 30 deletions(-)
>>
>> diff --git a/grub-core/loader/i386/xen.c b/grub-core/loader/i386/xen.c
>> index c4d9689..42ed7c7 100644
>> --- a/grub-core/loader/i386/xen.c
>> +++ b/grub-core/loader/i386/xen.c
>> @@ -52,6 +52,8 @@ static struct grub_xen_file_info xen_inf;
>> static struct xen_multiboot_mod_list *xen_module_info_page;
>> static grub_uint64_t modules_target_start;
>> static grub_size_t n_modules;
>> +static struct grub_relocator_xen_state state;
>> +static grub_xen_mfn_t *virt_mfn_list;
>
> Do we strongly need this as globals? I suppose that
> both of them could be local to grub_xen_boot.
This would require passing the state pointer to many other functions.
Same applies to virt_mfn_list.
I just followed the style used in the source already: variables used in
multiple functions are mostly defined globally (there are even some
which are used in one function only).
>
>> #define PAGE_SIZE 4096
>> #define MAX_MODULES (PAGE_SIZE / sizeof (struct xen_multiboot_mod_list))
>> @@ -166,7 +168,7 @@ generate_page_table (grub_uint64_t *where, grub_uint64_t
>> paging_start,
>> }
>>
>> static grub_err_t
>> -set_mfns (grub_xen_mfn_t * new_mfn_list, grub_xen_mfn_t pfn)
>> +set_mfns (grub_xen_mfn_t pfn)
>> {
>> grub_xen_mfn_t i, t;
>> grub_xen_mfn_t cn_pfn = -1, st_pfn = -1;
>> @@ -175,32 +177,32 @@ set_mfns (grub_xen_mfn_t * new_mfn_list,
>> grub_xen_mfn_t pfn)
>>
>> for (i = 0; i < grub_xen_start_page_addr->nr_pages; i++)
>> {
>> - if (new_mfn_list[i] == grub_xen_start_page_addr->console.domU.mfn)
>> + if (virt_mfn_list[i] == grub_xen_start_page_addr->console.domU.mfn)
>> cn_pfn = i;
>> - if (new_mfn_list[i] == grub_xen_start_page_addr->store_mfn)
>> + if (virt_mfn_list[i] == grub_xen_start_page_addr->store_mfn)
>> st_pfn = i;
>> }
>> if (cn_pfn == (grub_xen_mfn_t)-1)
>> return grub_error (GRUB_ERR_BUG, "no console");
>> if (st_pfn == (grub_xen_mfn_t)-1)
>> return grub_error (GRUB_ERR_BUG, "no store");
>> - t = new_mfn_list[pfn];
>> - new_mfn_list[pfn] = new_mfn_list[cn_pfn];
>> - new_mfn_list[cn_pfn] = t;
>> - t = new_mfn_list[pfn + 1];
>> - new_mfn_list[pfn + 1] = new_mfn_list[st_pfn];
>> - new_mfn_list[st_pfn] = t;
>> -
>> - m2p_updates[0].ptr = page2offset (new_mfn_list[pfn]) |
>> MMU_MACHPHYS_UPDATE;
>> + t = virt_mfn_list[pfn];
>> + virt_mfn_list[pfn] = virt_mfn_list[cn_pfn];
>> + virt_mfn_list[cn_pfn] = t;
>> + t = virt_mfn_list[pfn + 1];
>> + virt_mfn_list[pfn + 1] = virt_mfn_list[st_pfn];
>> + virt_mfn_list[st_pfn] = t;
>> +
>> + m2p_updates[0].ptr = page2offset (virt_mfn_list[pfn]) |
>> MMU_MACHPHYS_UPDATE;
>> m2p_updates[0].val = pfn;
>> m2p_updates[1].ptr =
>> - page2offset (new_mfn_list[pfn + 1]) | MMU_MACHPHYS_UPDATE;
>> + page2offset (virt_mfn_list[pfn + 1]) | MMU_MACHPHYS_UPDATE;
>> m2p_updates[1].val = pfn + 1;
>> m2p_updates[2].ptr =
>> - page2offset (new_mfn_list[cn_pfn]) | MMU_MACHPHYS_UPDATE;
>> + page2offset (virt_mfn_list[cn_pfn]) | MMU_MACHPHYS_UPDATE;
>> m2p_updates[2].val = cn_pfn;
>> m2p_updates[3].ptr =
>> - page2offset (new_mfn_list[st_pfn]) | MMU_MACHPHYS_UPDATE;
>> + page2offset (virt_mfn_list[st_pfn]) | MMU_MACHPHYS_UPDATE;
>> m2p_updates[3].val = st_pfn;
>>
>> grub_xen_mmu_update (m2p_updates, 4, NULL, DOMID_SELF);
>> @@ -209,34 +211,43 @@ set_mfns (grub_xen_mfn_t * new_mfn_list,
>> grub_xen_mfn_t pfn)
>> }
>>
>> static grub_err_t
>> +grub_xen_p2m_alloc (void)
>> +{
>> + grub_relocator_chunk_t ch;
>> + grub_size_t p2msize;
>> + grub_err_t err;
>> +
>> + state.mfn_list = max_addr;
>> + next_start.mfn_list = max_addr + xen_inf.virt_base;
>> + p2msize = sizeof (grub_xen_mfn_t) * grub_xen_start_page_addr->nr_pages;
>> + err = grub_relocator_alloc_chunk_addr (relocator, &ch, max_addr, p2msize);
>
> Hmmm.... Where relocator is defined?
First global variable in this source.
>
>> + if (err)
>> + return err;
>> + virt_mfn_list = get_virtual_current_address (ch);
>> + grub_memcpy (virt_mfn_list,
>> + (void *) grub_xen_start_page_addr->mfn_list, p2msize);
>> + max_addr = ALIGN_UP (max_addr + p2msize, PAGE_SIZE);
>> +
>> + return GRUB_ERR_NONE;
>> +}
>> +
>> +static grub_err_t
>> grub_xen_boot (void)
>> {
>> - struct grub_relocator_xen_state state;
>> grub_relocator_chunk_t ch;
>> grub_err_t err;
>> - grub_size_t pgtsize;
>> struct start_info *nst;
>> grub_uint64_t nr_info_pages;
>> grub_uint64_t nr_pages, nr_pt_pages, nr_need_pages;
>> struct gnttab_set_version gnttab_setver;
>> - grub_xen_mfn_t *new_mfn_list;
>> grub_size_t i;
>>
>> if (grub_xen_n_allocated_shared_pages)
>> return grub_error (GRUB_ERR_BUG, "active grants");
>>
>> - state.mfn_list = max_addr;
>> - next_start.mfn_list = max_addr + xen_inf.virt_base;
>> - next_start.first_p2m_pfn = max_addr >> PAGE_SHIFT; /* Is this
>> right? */
>> - pgtsize = sizeof (grub_xen_mfn_t) * grub_xen_start_page_addr->nr_pages;
>> - err = grub_relocator_alloc_chunk_addr (relocator, &ch, max_addr, pgtsize);
>> - next_start.nr_p2m_frames = (pgtsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
>> + err = grub_xen_p2m_alloc ();
>> if (err)
>> return err;
>> - new_mfn_list = get_virtual_current_address (ch);
>> - grub_memcpy (new_mfn_list,
>> - (void *) grub_xen_start_page_addr->mfn_list, pgtsize);
>> - max_addr = ALIGN_UP (max_addr + pgtsize, PAGE_SIZE);
>>
>> err = grub_relocator_alloc_chunk_addr (relocator, &ch,
>
> Ditto. I think that this could be passed as a grub_xen_boot() argument.
> Otherwise this appear from nowhere and reading/understanding is more
> difficult.
Huh? How that? grub_xen_boot() can't have any parameters (see prototype
of grub_loader_set() which is used with grub_xen_boot() as parameter).
BTW: I didn't introduce this kind of usage of relocator.
Juergen
- [PATCH v2 4/6] xen: add capability to load initrd outside of initial mapping, (continued)
[PATCH v2 1/6] xen: factor out p2m list allocation into separate function, Juergen Gross, 2016/02/11
[PATCH v2 3/6] xen: factor out allocation of page tables into separate function, Juergen Gross, 2016/02/11
[PATCH v2 5/6] xen: modify page table construction, Juergen Gross, 2016/02/11