[PATCH v6 08/10] x86/sev: Handle CLFLUSH MMIO events

From: vsntk18@gmail.com
To: vsntk18@gmail.com
Cc: x86@kernel.org, Borislav.Petkov@amd.com, Dhaval.Giani@amd.com,
	ashish.kalra@amd.com, cfir@google.com, dan.j.williams@intel.com,
	dave.hansen@linux.intel.com, ebiederm@xmission.com,
	erdemaktas@google.com, hpa@zytor.com, jgross@suse.com,
	jroedel@suse.de, jslaby@suse.cz, keescook@chromium.org,
	kexec@lists.infradead.org, kvm@vger.kernel.org,
	linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org,
	luto@kernel.org, martin.b.radev@gmail.com, mhiramat@kernel.org,
	michael.roth@amd.com, mstunes@vmware.com, nivedita@alum.mit.edu,
	peterz@infradead.org, rientjes@google.com, seanjc@google.com,
	stable@vger.kernel.org, thomas.lendacky@amd.com,
	virtualization@lists.linux-foundation.org, vkarasulli@suse.de
Subject: [PATCH v6 08/10] x86/sev: Handle CLFLUSH MMIO events
Date: Mon, 10 Jun 2024 12:21:11 +0200	[thread overview]
Message-ID: <20240610102113.20969-9-vsntk18@gmail.com> (raw)
In-Reply-To: <20240610102113.20969-1-vsntk18@gmail.com>

From: Joerg Roedel <jroedel@suse.de>

Handle CLFLUSH instruction to MMIO memory in the #VC handler. The
instruction is ignored by the handler, as the Hypervisor is
responsible for cache management of emulated MMIO memory.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Vasant Karasulli <vkarasulli@suse.de>
---
 arch/x86/include/asm/insn-eval.h | 1 +
 arch/x86/kernel/sev-shared.c     | 3 +++
 arch/x86/lib/insn-eval-shared.c  | 7 +++++++
 3 files changed, 11 insertions(+)

diff --git a/arch/x86/include/asm/insn-eval.h b/arch/x86/include/asm/insn-eval.h
index 54368a43abf6..3bcea641913a 100644
--- a/arch/x86/include/asm/insn-eval.h
+++ b/arch/x86/include/asm/insn-eval.h
@@ -40,6 +40,7 @@ enum insn_mmio_type {
 	INSN_MMIO_READ_ZERO_EXTEND,
 	INSN_MMIO_READ_SIGN_EXTEND,
 	INSN_MMIO_MOVS,
+	INSN_MMIO_IGNORE,
 };
 
 enum insn_mmio_type insn_decode_mmio(struct insn *insn, int *bytes);
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index 1b25a6cacec7..2a963ad84f10 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -1171,6 +1171,9 @@ static enum es_result vc_handle_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 	if (mmio == INSN_MMIO_DECODE_FAILED)
 		return ES_DECODE_FAILED;
 
+	if (mmio == INSN_MMIO_IGNORE)
+		return ES_OK;
+
 	if (mmio != INSN_MMIO_WRITE_IMM && mmio != INSN_MMIO_MOVS) {
 		reg_data = insn_get_modrm_reg_ptr(insn, ctxt->regs);
 		if (!reg_data)
diff --git a/arch/x86/lib/insn-eval-shared.c b/arch/x86/lib/insn-eval-shared.c
index 02acdc2921ff..27fd347d84ae 100644
--- a/arch/x86/lib/insn-eval-shared.c
+++ b/arch/x86/lib/insn-eval-shared.c
@@ -906,6 +906,13 @@ enum insn_mmio_type insn_decode_mmio(struct insn *insn, int *bytes)
 				*bytes = 2;
 			type = INSN_MMIO_READ_SIGN_EXTEND;
 			break;
+		case 0xae: /* CLFLUSH */
+			/*
+			 * Ignore CLFLUSHes - those go to emulated MMIO anyway and the
+			 * hypervisor is responsible for cache management.
+			 */
+			type = INSN_MMIO_IGNORE;
+			break;
 		}
 		break;
 	}
-- 
2.34.1


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