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* [PATCH] x86/sgx: Fix free_cnt counting logic in epc section
@ 2021-01-18 13:33 Tianjia Zhang
  2021-01-19 20:24 ` Sean Christopherson
  2021-01-20 14:36 ` Jarkko Sakkinen
  0 siblings, 2 replies; 3+ messages in thread
From: Tianjia Zhang @ 2021-01-18 13:33 UTC (permalink / raw)
  To: Jarkko Sakkinen, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
	H. Peter Anvin, Andrew Morton, Shuah Khan, haitao.huang,
	Kai Huang, x86, linux-sgx, linux-kernel, linux-mm,
	linux-kselftest, Jia Zhang
  Cc: Tianjia Zhang

Increase `section->free_cnt` in sgx_sanitize_section() is
more reasonable, which is called in ksgxd kernel thread,
instead of assigning it to epc section pages number at
initialization. Although this is unlikely to fail, these
pages cannot be allocated after initialization, and which
need to be reset by ksgxd.

Reported-by: Jia Zhang <zhang.jia@linux.alibaba.com>
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
---
 arch/x86/kernel/cpu/sgx/main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index c519fc5f6948..9e9a3cf7c00b 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -48,9 +48,10 @@ static void sgx_sanitize_section(struct sgx_epc_section *section)
 					struct sgx_epc_page, list);
 
 		ret = __eremove(sgx_get_epc_virt_addr(page));
-		if (!ret)
+		if (!ret) {
 			list_move(&page->list, &section->page_list);
-		else
+			section->free_cnt += 1;
+		} else
 			list_move_tail(&page->list, &dirty);
 
 		spin_unlock(&section->lock);
@@ -646,7 +647,6 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 		list_add_tail(&section->pages[i].list, &section->init_laundry_list);
 	}
 
-	section->free_cnt = nr_pages;
 	return true;
 }
 
-- 
2.19.1.3.ge56e4f7


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2021-01-18 13:33 [PATCH] x86/sgx: Fix free_cnt counting logic in epc section Tianjia Zhang
2021-01-19 20:24 ` Sean Christopherson
2021-01-20 14:36 ` Jarkko Sakkinen

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