x86/sev-es: Use __copy_from_user_inatomic()

stable inclusion
from stable-5.10.24
commit a2bab396cb97f5a6468f54caca0d25b23b75539c
bugzilla: 51348

--------------------------------

commit bffe30dd upstream.

The #VC handler must run in atomic context and cannot sleep. This is a
problem when it tries to fetch instruction bytes from user-space via
copy_from_user().

Introduce a insn_fetch_from_user_inatomic() helper which uses
__copy_from_user_inatomic() to safely copy the instruction bytes to
kernel memory in the #VC handler.

Fixes: 5e3427a7 ("x86/sev-es: Handle instruction fetches from user-space")
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: stable@vger.kernel.org # v5.10+
Link: https://lkml.kernel.org/r/20210303141716.29223-6-joro@8bytes.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by:   Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>