linux-kernel - [RFC PATCH V3 09/16] x86/hyperv: SEV-SNP enlightened guest don't support legacy rtc

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Message-Id: <20230122024607.788454-10-ltykernel@gmail.com>
Date:   Sat, 21 Jan 2023 21:45:59 -0500
From:   Tianyu Lan <ltykernel@...il.com>
To:     luto@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, seanjc@...gle.com, pbonzini@...hat.com,
        jgross@...e.com, tiala@...rosoft.com, kirill@...temov.name,
        jiangshan.ljs@...group.com, peterz@...radead.org,
        ashish.kalra@....com, srutherford@...gle.com,
        akpm@...ux-foundation.org, anshuman.khandual@....com,
        pawan.kumar.gupta@...ux.intel.com, adrian.hunter@...el.com,
        daniel.sneddon@...ux.intel.com, alexander.shishkin@...ux.intel.com,
        sandipan.das@....com, ray.huang@....com, brijesh.singh@....com,
        michael.roth@....com, thomas.lendacky@....com,
        venu.busireddy@...cle.com, sterritt@...gle.com,
        tony.luck@...el.com, samitolvanen@...gle.com, fenghua.yu@...el.com
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-hyperv@...r.kernel.org, linux-arch@...r.kernel.org
Subject: [RFC PATCH V3 09/16] x86/hyperv: SEV-SNP enlightened guest don't support legacy rtc

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

SEV-SNP enlightened guest doesn't support legacy rtc. Set
legacy.rtc, x86_platform.set_wallclock and get_wallclock to
0 or noop(). Make get/set_rtc_noop() to be public and reuse
them in the ms_hyperv_init_platform().

Signed-off-by: Tianyu Lan <tiala@...rosoft.com>
---
 arch/x86/include/asm/mshyperv.h | 7 ++++++-
 arch/x86/include/asm/x86_init.h | 2 ++
 arch/x86/kernel/cpu/mshyperv.c  | 3 +++
 arch/x86/kernel/x86_init.c      | 4 ++--
 4 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 1a4af0a4f29a..7266d71d30d6 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -33,6 +33,12 @@ extern bool hv_isolation_type_en_snp(void);
 
 extern union hv_ghcb * __percpu *hv_ghcb_pg;
 
+/*
+ * Hyper-V puts processor and memory layout info
+ * to this address in SEV-SNP enlightened guest.
+ */
+#define EN_SEV_SNP_PROCESSOR_INFO_ADDR	0x802000
+
 int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
 int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id);
 int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags);
@@ -267,7 +273,6 @@ static inline void hv_set_register(unsigned int reg, u64 value) { }
 static inline u64 hv_get_register(unsigned int reg) { return 0; }
 #endif /* CONFIG_HYPERV */
 
-
 #include <asm-generic/mshyperv.h>
 
 #endif
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index c1c8c581759d..d8fb3a1639e9 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -326,5 +326,7 @@ extern void x86_init_uint_noop(unsigned int unused);
 extern bool bool_x86_init_noop(void);
 extern void x86_op_int_noop(int cpu);
 extern bool x86_pnpbios_disabled(void);
+extern int set_rtc_noop(const struct timespec64 *now);
+extern void get_rtc_noop(struct timespec64 *now);
 
 #endif
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index b1871a7bb4c9..197c8f2ec4eb 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -508,6 +508,9 @@ static void __init ms_hyperv_init_platform(void)
 		 * bios regions and reserve resources are not
 		 * available. Set these callback to NULL.
 		 */
+		x86_platform.legacy.rtc = 0;
+		x86_platform.set_wallclock = set_rtc_noop;
+		x86_platform.get_wallclock = get_rtc_noop;
 		x86_platform.legacy.reserve_bios_regions = x86_init_noop;
 		x86_init.resources.probe_roms = x86_init_noop;
 		x86_init.resources.reserve_resources = x86_init_noop;
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index ef80d361b463..d93aeffec19b 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -33,8 +33,8 @@ static int __init iommu_init_noop(void) { return 0; }
 static void iommu_shutdown_noop(void) { }
 bool __init bool_x86_init_noop(void) { return false; }
 void x86_op_int_noop(int cpu) { }
-static __init int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
-static __init void get_rtc_noop(struct timespec64 *now) { }
+int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
+void get_rtc_noop(struct timespec64 *now) { }
 
 static __initconst const struct of_device_id of_cmos_match[] = {
 	{ .compatible = "motorola,mc146818" },
-- 
2.25.1