From: Joerg Roedel jroedel@suse.de
This reverts commit 7024f60d655272bd2ca1d3a4c9e0a63319b1eea1.
The commit reverted here introduces a short-cut into the #VC handlers memory access code which only works reliably in task context. But the kernels #VC handler can be invoked from any context, making the access_ok() call trigger a warning with CONFIG_DEBUG_ATOMIC_SLEEP enabled.
Also the memcpy() used in the reverted patch is wrong, as it has no page-fault handling. Access to kernel memory can also fault due to kernel bugs, and those should not be reported as faults from the #VC handler but as bugs of their real call-site, which is correctly later done from vc_forward_exception().
Fixes: 7024f60d6552 ("x86/sev-es: Handle string port IO to kernel memory properly") Cc: stable@vger.kernel.org # v5.11 Signed-off-by: Joerg Roedel jroedel@suse.de --- arch/x86/kernel/sev.c | 12 ------------ 1 file changed, 12 deletions(-)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 110b39345b40..f4f319004713 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -333,12 +333,6 @@ static enum es_result vc_write_mem(struct es_em_ctxt *ctxt, u16 d2; u8 d1;
- /* If instruction ran in kernel mode and the I/O buffer is in kernel space */ - if (!user_mode(ctxt->regs) && !access_ok(target, size)) { - memcpy(dst, buf, size); - return ES_OK; - } - switch (size) { case 1: memcpy(&d1, buf, 1); @@ -388,12 +382,6 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt, u16 d2; u8 d1;
- /* If instruction ran in kernel mode and the I/O buffer is in kernel space */ - if (!user_mode(ctxt->regs) && !access_ok(s, size)) { - memcpy(buf, src, size); - return ES_OK; - } - switch (size) { case 1: if (__get_user(d1, s))