linux-kernel - [PATCH 52/70] x86/sev-es: Handle RDTSC Events

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Date:   Thu, 19 Mar 2020 10:13:49 +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 52/70] x86/sev-es: Handle RDTSC Events

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

Implement a handler for #VC exceptions caused by RDTSC instructions.

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 | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index 5b024ee54307..afbe574126f3 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -665,6 +665,23 @@ static enum es_result vc_handle_wbinvd(struct ghcb *ghcb,
 	return sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WBINVD, 0, 0);
 }
 
+static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
+{
+	enum es_result ret;
+
+	ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_RDTSC, 0, 0);
+	if (ret != ES_OK)
+		return ret;
+
+	if (!(ghcb_is_valid_rax(ghcb) && ghcb_is_valid_rdx(ghcb)))
+		return ES_VMM_ERROR;
+
+	ctxt->regs->ax = ghcb->save.rax;
+	ctxt->regs->dx = ghcb->save.rdx;
+
+	return ES_OK;
+}
+
 static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
 					 struct ghcb *ghcb,
 					 unsigned long exit_code,
@@ -679,6 +696,9 @@ static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
 	case SVM_EXIT_WRITE_DR7:
 		result = vc_handle_dr7_write(ghcb, ctxt, early);
 		break;
+	case SVM_EXIT_RDTSC:
+		result = vc_handle_rdtsc(ghcb, ctxt);
+		break;
 	case SVM_EXIT_CPUID:
 		result = vc_handle_cpuid(ghcb, ctxt);
 		break;
-- 
2.17.1