[tip: x86/urgent] x86/sgx: Handle VA page allocation failure for EAUG on PF.

[tip-bot2 for Haitao Huang]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     81fa6fd13b5c43601fba8486f2385dbd7c1935e2
Gitweb:        https://git.kernel.org/tip/81fa6fd13b5c43601fba8486f2385dbd7c1935e2
Author:        Haitao Huang <haitao.huang@xxxxxxxxxxxxxxx>
AuthorDate:    Tue, 06 Sep 2022 03:02:21 +03:00
Committer:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Thu, 08 Sep 2022 13:28:31 -07:00

x86/sgx: Handle VA page allocation failure for EAUG on PF.

VM_FAULT_NOPAGE is expected behaviour for -EBUSY failure path, when
augmenting a page, as this means that the reclaimer thread has been
triggered, and the intention is just to round-trip in ring-3, and
retry with a new page fault.

Fixes: 5a90d2c3f5ef ("x86/sgx: Support adding of pages to an initialized enclave")
Signed-off-by: Haitao Huang <haitao.huang@xxxxxxxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Tested-by: Vijay Dhanraj <vijay.dhanraj@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20220906000221.34286-3-jarkko@xxxxxxxxxx
---
 arch/x86/kernel/cpu/sgx/encl.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 24c1bb8..8bdeae2 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -344,8 +344,11 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
 	}
 
 	va_page = sgx_encl_grow(encl, false);
-	if (IS_ERR(va_page))
+	if (IS_ERR(va_page)) {
+		if (PTR_ERR(va_page) == -EBUSY)
+			vmret = VM_FAULT_NOPAGE;
 		goto err_out_epc;
+	}
 
 	if (va_page)
 		list_add(&va_page->list, &encl->va_pages);