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

vsntk18
2024-06-10T10:21:41Z

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