linux-kernel - [RFC PATCH V4 09/17] x86/hyperv: SEV-SNP enlightened guest don't support legacy rtc

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Message-Id: <20230403174406.4180472-10-ltykernel@gmail.com>
Date:   Mon,  3 Apr 2023 13:43:57 -0400
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:     pangupta@....com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-hyperv@...r.kernel.org,
        linux-arch@...r.kernel.org
Subject: [RFC PATCH V4 09/17] 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/hyperv/ivm.c           | 3 +++
 arch/x86/include/asm/x86_init.h | 2 ++
 arch/x86/kernel/x86_init.c      | 4 ++--
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index fa4de2761460..c0f3fa924163 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -391,6 +391,9 @@ __init void hv_sev_init_mem_and_cpu(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 = 0;
 	x86_init.resources.probe_roms = x86_init_noop;
 	x86_init.resources.reserve_resources = x86_init_noop;
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 6f873c686cd3..e5a6f9baec67 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -330,5 +330,7 @@ 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/x86_init.c b/arch/x86/kernel/x86_init.c
index 95be3831df73..d82f4fa2f1bf 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