linux-kernel - [PATCH 50/62] x86/sev-es: Handle VMMCALL Events

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Message-Id: <20200211135256.24617-51-joro@8bytes.org>
Date:   Tue, 11 Feb 2020 14:52:44 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     x86@...nel.org
Cc:     hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Joerg Roedel <joro@...tes.org>, Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 50/62] x86/sev-es: Handle VMMCALL Events

From: Tom Lendacky <thomas.lendacky@....com>

Implement a handler for #VC exceptions caused by VMMCALL instructions.
This patch is only a starting point, VMMCALL emulation under SEV-ES
needs further hypervisor-specific changes to provide additional state.

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
[ jroedel@...e.de: Adapt to #VC handling infrastructure ]
Co-developed-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 arch/x86/kernel/sev-es.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index 8f1e84da6fa6..6bd2cae7eb9c 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -341,6 +341,26 @@ static enum es_result handle_mwait(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 	return ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MWAIT, 0, 0);
 }
 
+static enum es_result handle_vmmcall(struct ghcb *ghcb,
+				     struct es_em_ctxt *ctxt)
+{
+	enum es_result ret;
+
+	ghcb_set_rax(ghcb, ctxt->regs->ax);
+	ghcb_set_cpl(ghcb, user_mode(ctxt->regs) ? 3 : 0);
+
+	ret = ghcb_hv_call(ghcb, ctxt, SVM_EXIT_VMMCALL, 0, 0);
+	if (ret != ES_OK)
+		return ret;
+
+	if (!ghcb_is_valid_rax(ghcb))
+		return ES_VMM_ERROR;
+
+	ctxt->regs->ax = ghcb->save.rax;
+
+	return ES_OK;
+}
+
 static enum es_result handle_vc_exception(struct es_em_ctxt *ctxt,
 					  struct ghcb *ghcb,
 					  unsigned long exit_code,
@@ -374,6 +394,9 @@ static enum es_result handle_vc_exception(struct es_em_ctxt *ctxt,
 	case SVM_EXIT_MSR:
 		result = handle_msr(ghcb, ctxt);
 		break;
+	case SVM_EXIT_VMMCALL:
+		result = handle_vmmcall(ghcb, ctxt);
+		break;
 	case SVM_EXIT_WBINVD:
 		result = handle_wbinvd(ghcb, ctxt);
 		break;
-- 
2.17.1