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@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Vijay Dhanraj <vijay.dhanraj@intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20220906000221.34286-3-jarkko@kernel.org

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 24c1bb8eb196252708444245e8b5b684c68d184a..8bdeae2fc3091a65e07a6cfa48154e18e820929f 100644 (file)
--- 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);