linux-kernel - [PATCH 2/5 V5] Allocate pages for kdump without encryption when SME is enabled

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Date:   Mon,  2 Jul 2018 15:26:36 +0800
From:   Lianbo Jiang <lijiang@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...hat.com, tglx@...utronix.de, hpa@...or.com,
        ebiederm@...ssion.com, joro@...tes.org, thomas.lendacky@....com,
        dyoung@...hat.com, kexec@...ts.infradead.org,
        iommu@...ts.linux-foundation.org, bhe@...hat.com
Subject: [PATCH 2/5 V5] Allocate pages for kdump without encryption when SME is enabled

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@...hat.com>
---
Some changes:
1. remove some redundant codes for crash control pages.
2. add some comments.

 kernel/kexec_core.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 23a83a4..e7efcd1 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) {
+		/*
+		 * For kdump, we need to ensure that these pages are
+		 * unencrypted pages if SME is enabled.
+		 * By the way, it is unnecessary to call the arch_
+		 * kexec_pre_free_pages(), which will make the code
+		 * become more simple.
+		 */
+		arch_kexec_post_alloc_pages(page_address(pages), 1 << order, 0);
+	}
 	return pages;
 }
 
@@ -867,6 +877,7 @@ 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,
@@ -884,6 +895,7 @@ 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