linux-kernel - Re: [tip:x86/mm] kdump, proc/vmcore: Enable kdumping encrypted memory with SME enabled

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Date:   Mon, 8 Oct 2018 15:43:59 +0200
From:   Borislav Petkov <bp@...e.de>
To:     lijiang <lijiang@...hat.com>
Cc:     linux-kernel@...r.kernel.org, mingo@...nel.org, tglx@...utronix.de,
        hpa@...or.com, linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/mm] kdump, proc/vmcore: Enable kdumping encrypted
 memory with SME enabled

On Mon, Oct 08, 2018 at 10:59:09AM +0200, Borislav Petkov wrote:
> On Mon, Oct 08, 2018 at 04:47:34PM +0800, lijiang wrote:
> > It looks like a good way to avoid the 'ifdefined', and it's also good enough for i386.
> > 
> > But for other architectures, such as POWERPC/ARM..., we will also have to add the same 
> > function for every architecture. Otherwise, i guess that they also have a same compile
> > error on other architectures.
> 
> Yap, just realized that and looking at the rest of fs/proc/vmcore.c -
> such functions are defined with the __weak attribute. Lemme see if that
> works better.

Seems so. I'll hammer on it more today:

---
 fs/proc/vmcore.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 42c32d06f7da..91ae16fbd7d5 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -187,6 +187,16 @@ int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma,
 	return remap_pfn_range(vma, from, pfn, size, prot);
 }
 
+/*
+ * Architectures which support memory encryption override this.
+ */
+ssize_t __weak
+copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
+			   unsigned long offset, int userbuf)
+{
+	return copy_oldmem_page(pfn, buf, csize, offset, userbuf);
+}
+
 /*
  * Copy to either kernel or user space
  */
-- 
2.19.0.271.gfe8321ec057f

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)