linux-kernel - [PATCH V7 5/9] x86/sev-es: Expose __sev_es_ghcb_hv_call() to call ghcb hv call out of sev code

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Message-Id: <20211006063651.1124737-6-ltykernel@gmail.com>
Date:   Wed,  6 Oct 2021 02:36:45 -0400
From:   Tianyu Lan <ltykernel@...il.com>
To:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        wei.liu@...nel.org, decui@...rosoft.com, tglx@...utronix.de,
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        dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
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        Tianyu.Lan@...rosoft.com, thomas.lendacky@....com,
        pgonda@...gle.com, akpm@...ux-foundation.org,
        kirill.shutemov@...ux.intel.com, rppt@...nel.org, tj@...nel.org,
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Cc:     linux-arch@...r.kernel.org, linux-hyperv@...r.kernel.org,
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        dave.hansen@...el.com
Subject: [PATCH V7 5/9] x86/sev-es: Expose __sev_es_ghcb_hv_call() to call ghcb hv call out of sev code

From: Tianyu Lan <Tianyu.Lan@...rosoft.com>

Hyper-V also needs to call ghcb hv call to write/read MSR in Isolation VM.
So expose __sev_es_ghcb_hv_call() to call it in the Hyper-V code.

Signed-off-by: Tianyu Lan <Tianyu.Lan@...rosoft.com>
---
 arch/x86/include/asm/sev.h   | 10 +++++++++
 arch/x86/kernel/sev-shared.c | 43 +++++++++++++++++++++++++-----------
 2 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index fa5cd05d3b5b..2e96869f3e9b 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -81,12 +81,22 @@ static __always_inline void sev_es_nmi_complete(void)
 		__sev_es_nmi_complete();
 }
 extern int __init sev_es_efi_map_ghcbs(pgd_t *pgd);
+extern enum es_result __sev_es_ghcb_hv_call(struct ghcb *ghcb,
+					    u64 exit_code, u64 exit_info_1,
+					    u64 exit_info_2);
 #else
 static inline void sev_es_ist_enter(struct pt_regs *regs) { }
 static inline void sev_es_ist_exit(void) { }
 static inline int sev_es_setup_ap_jump_table(struct real_mode_header *rmh) { return 0; }
 static inline void sev_es_nmi_complete(void) { }
 static inline int sev_es_efi_map_ghcbs(pgd_t *pgd) { return 0; }
+static inline enum es_result
+__sev_es_ghcb_hv_call(struct ghcb *ghcb,
+		      u64 exit_code, u64 exit_info_1,
+		      u64 exit_info_2)
+{
+	return ES_VMM_ERROR;
+}
 #endif
 
 #endif
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index 9f90f460a28c..946c203be08c 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -94,10 +94,13 @@ static void vc_finish_insn(struct es_em_ctxt *ctxt)
 	ctxt->regs->ip += ctxt->insn.length;
 }
 
-static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
-					  struct es_em_ctxt *ctxt,
-					  u64 exit_code, u64 exit_info_1,
-					  u64 exit_info_2)
+/*
+ * __sev_es_ghcb_hv_call() is also used in the other platform code(e.g
+ * Hyper-V).
+ */
+enum es_result __sev_es_ghcb_hv_call(struct ghcb *ghcb,
+				     u64 exit_code, u64 exit_info_1,
+				     u64 exit_info_2)
 {
 	enum es_result ret;
 
@@ -109,15 +112,33 @@ static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
 	ghcb_set_sw_exit_info_1(ghcb, exit_info_1);
 	ghcb_set_sw_exit_info_2(ghcb, exit_info_2);
 
-	sev_es_wr_ghcb_msr(__pa(ghcb));
 	VMGEXIT();
 
+	if (ghcb->save.sw_exit_info_1 & 0xffffffff)
+		ret = ES_VMM_ERROR;
+	else
+		ret = ES_OK;
+
+	return ret;
+}
+
+static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
+					  struct es_em_ctxt *ctxt,
+					  u64 exit_code, u64 exit_info_1,
+					  u64 exit_info_2)
+{
+	enum es_result ret;
+
+	sev_es_wr_ghcb_msr(__pa(ghcb));
+
+	ret = __sev_es_ghcb_hv_call(ghcb, exit_code, exit_info_1,
+					 exit_info_2);
+	if (ret == ES_OK)
+		return ret;
+
 	if ((ghcb->save.sw_exit_info_1 & 0xffffffff) == 1) {
 		u64 info = ghcb->save.sw_exit_info_2;
-		unsigned long v;
-
-		info = ghcb->save.sw_exit_info_2;
-		v = info & SVM_EVTINJ_VEC_MASK;
+		unsigned long v = info & SVM_EVTINJ_VEC_MASK;
 
 		/* Check if exception information from hypervisor is sane. */
 		if ((info & SVM_EVTINJ_VALID) &&
@@ -127,11 +148,7 @@ static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
 			if (info & SVM_EVTINJ_VALID_ERR)
 				ctxt->fi.error_code = info >> 32;
 			ret = ES_EXCEPTION;
-		} else {
-			ret = ES_VMM_ERROR;
 		}
-	} else {
-		ret = ES_OK;
 	}
 
 	return ret;
-- 
2.25.1