Re: [PATCH 2/4 V3] Allocate pages for kdump without encryption when SME is enabled

Baoquan He
2018-06-21T10:23:30Z

On 06/21/18 at 01:06pm, lijiang wrote:
> 在 2018年06月21日 09:53, Baoquan He 写道:
> > On 06/16/18 at 04:27pm, Lianbo Jiang wrote:
> >> When SME is enabled in the first kernel, we will allocate pages
> >> for kdump without encryption in order to be able to boot the
> >> second kernel in the same manner as kexec, which helps to keep
> >> the same code style.
> >>
> >> Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
> >> ---
> >> kernel/kexec_core.c | 12 ++++++++++++
> >> 1 file changed, 12 insertions(+)
> >>
> >> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> >> index 20fef1a..3c22a9b 100644
> >> --- a/kernel/kexec_core.c
> >> +++ b/kernel/kexec_core.c
> >> @@ -471,6 +471,16 @@ static struct page *kimage_alloc_crash_control_pages(struct kimage *image,
> >> }
> >> }
> >>
> >> + if (pages) {
> >> + unsigned int count, i;
> >> +
> >> + pages->mapping = NULL;
> >> + set_page_private(pages, order);
> >> + count = 1 << order;
> >> + for (i = 0; i < count; i++)
> >> + SetPageReserved(pages + i);
> >
> > I guess you might imitate the kexec case, however kexec get pages from
> > buddy. Crash pages are reserved in memblock, these codes might make no sense.
> >
> Thanks for your comments.
> We have changed the attribute of pages, so the original attribute of pages will be
> restored when they free.

Hmm, you can check what kimage_free() is doing, and where
kimage->control_pages, dest_pages, unusable_pages is assigned. Do you
know where these original attribute of pages comes from and they are
used/needed in CRASH case, if you care about them?

>
> >> + arch_kexec_post_alloc_pages(page_address(pages), 1 << order, 0);
> >> + }
> >> return pages;
> >> }
> >>
> >> @@ -865,6 +875,7 @@ static int kimage_load_crash_segment(struct kimage *image,
> >> result = -ENOMEM;
> >> goto out;
> >> }
> >> + arch_kexec_post_alloc_pages(page_address(page), 1, 0);
> >> ptr = kmap(page);
> >> ptr += maddr & ~PAGE_MASK;
> >> mchunk = min_t(size_t, mbytes,
> >> @@ -882,6 +893,7 @@ static int kimage_load_crash_segment(struct kimage *image,
> >> result = copy_from_user(ptr, buf, uchunk);
> >> kexec_flush_icache_page(page);
> >> kunmap(page);
> >> + arch_kexec_pre_free_pages(page_address(page), 1);
> >> if (result) {
> >> result = -EFAULT;
> >> goto out;
> >> --
> >> 2.9.5
> >>
> >>
> >> _______________________________________________
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> >> http://lists.infradead.org/mailman/listinfo/kexec