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

Handle #VC exceptions caused by #DB exceptions in the guest. Do not
forward them to the hypervisor and handle them with do_debug() instead.

Signed-off-by: Joerg Roedel <jroe...@suse.de>
---
 arch/x86/kernel/sev-es.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index 050a15da9ae5..03095bc7b563 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -882,6 +882,19 @@ static enum es_result vc_handle_trap_ac(struct ghcb *ghcb,
        return ES_EXCEPTION;
 }
 
+static enum es_result vc_handle_trap_db(struct ghcb *ghcb,
+                                       struct es_em_ctxt *ctxt)
+{
+       /*
+        * Calling do_debug() directly does not work, because it might enable
+        * IRQs and the GHCB is active. Forward the exception and call it later
+        * from vc_forward_exception().
+        */
+       ctxt->fi.vector = X86_TRAP_DB;
+       ctxt->fi.error_code = 0;
+       return ES_EXCEPTION;
+}
+
 static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
                                         struct ghcb *ghcb,
                                         unsigned long exit_code)
@@ -895,6 +908,9 @@ static enum es_result vc_handle_exitcode(struct es_em_ctxt 
*ctxt,
        case SVM_EXIT_WRITE_DR7:
                result = vc_handle_dr7_write(ghcb, ctxt);
                break;
+       case SVM_EXIT_EXCP_BASE + X86_TRAP_DB:
+               result = vc_handle_trap_db(ghcb, ctxt);
+               break;
        case SVM_EXIT_EXCP_BASE + X86_TRAP_AC:
                result = vc_handle_trap_ac(ghcb, ctxt);
                break;
@@ -960,6 +976,9 @@ static void vc_forward_exception(struct es_em_ctxt *ctxt)
        case X86_TRAP_AC:
                do_alignment_check(ctxt->regs, error_code);
                break;
+       case X86_TRAP_DB:
+               do_debug(ctxt->regs, error_code);
+               break;
        default:
                pr_emerg("Unsupported exception in #VC instruction emulation - 
can't continue\n");
                BUG();
-- 
2.17.1

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