[PATCH 1/2] x86/sgx: Handle VA page allocation failure for EAUG on PF.

[Jarkko Sakkinen]

From: Haitao Huang <haitao.huang@xxxxxxxxxxxxxxx>

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>
Tested-by: Vijay Dhanraj <vijay.dhanraj@xxxxxxxxx>
Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
---
I rewrote the commit message because it was not explanatory enough,
added the missing fixes tag, and all cumulated tags.
 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 24c1bb8eb196..de92c1c8b79d 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);
-- 
2.37.1