From: Joerg Roedel <jroe...@suse.de>

Handle #VC exceptions caused by #DB exceptions in the guest. Those
must be handled outside of instrumentation_begin()/end() so that the
handler will not be raised recursivly.

Handle them by calling the kernels debug exception handler.

Signed-off-by: Joerg Roedel <jroe...@suse.de>
Link: https://lore.kernel.org/r/20200724160336.5435-64-j...@8bytes.org
---
 arch/x86/kernel/sev-es.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index ee0950f01590..e1f3ebbcc122 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -922,6 +922,14 @@ static enum es_result vc_handle_trap_ac(struct ghcb *ghcb,
        return ES_EXCEPTION;
 }
 
+static __always_inline void vc_handle_trap_db(struct pt_regs *regs)
+{
+       if (user_mode(regs))
+               noist_exc_debug(regs);
+       else
+               exc_debug(regs);
+}
+
 static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
                                         struct ghcb *ghcb,
                                         unsigned long exit_code)
@@ -1033,6 +1041,15 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
        struct ghcb *ghcb;
 
        lockdep_assert_irqs_disabled();
+
+       /*
+        * Handle #DB before calling into !noinstr code to avoid recursive #DB.
+        */
+       if (error_code == SVM_EXIT_EXCP_BASE + X86_TRAP_DB) {
+               vc_handle_trap_db(regs);
+               return;
+       }
+
        instrumentation_begin();
 
        /*
-- 
2.28.0

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Reply via email to