linux-kernel - [PATCH 41/62] x86/sev-es: Handle MSR events

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Message-Id: <20200211135256.24617-42-joro@8bytes.org>
Date:   Tue, 11 Feb 2020 14:52:35 +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 41/62] x86/sev-es: Handle MSR events

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

Implement a handler for #VC exceptions caused by RDMSR/WRMSR
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 | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index 84b5b8f7897a..b27d5b0a8ae1 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -134,6 +134,35 @@ static phys_addr_t es_slow_virt_to_phys(struct ghcb *ghcb, long vaddr)
 /* Include code shared with pre-decompression boot stage */
 #include "sev-es-shared.c"
 
+static enum es_result handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
+{
+	struct pt_regs *regs = ctxt->regs;
+	enum es_result ret;
+	bool write;
+	u64 exit_info_1;
+
+	write = (ctxt->insn.opcode.bytes[1] == 0x30);
+
+	ghcb_set_rcx(ghcb, regs->cx);
+	if (write) {
+		ghcb_set_rax(ghcb, regs->ax);
+		ghcb_set_rdx(ghcb, regs->dx);
+		exit_info_1 = 1;
+	} else {
+		exit_info_1 = 0;
+	}
+
+	ret = ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, exit_info_1, 0);
+	if (ret != ES_OK)
+		return ret;
+	else if (!write) {
+		regs->ax = ghcb->save.rax;
+		regs->dx = ghcb->save.rdx;
+	}
+
+	return ret;
+}
+
 /*
  * This function runs on the first #VC exception after the kernel
  * switched to virtual addresses.
@@ -196,6 +225,9 @@ static enum es_result handle_vc_exception(struct es_em_ctxt *ctxt,
 	case SVM_EXIT_IOIO:
 		result = handle_ioio(ghcb, ctxt);
 		break;
+	case SVM_EXIT_MSR:
+		result = handle_msr(ghcb, ctxt);
+		break;
 	case SVM_EXIT_NPF:
 		result = handle_mmio(ghcb, ctxt);
 		break;
-- 
2.17.1