linux-kernel - [PATCH v2 16/38] x86/vmware: Nullify save/restore hooks when using VMware's sched

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Message-ID: <20250227021855.3257188-17-seanjc@google.com>
Date: Wed, 26 Feb 2025 18:18:32 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Sean Christopherson <seanjc@...gle.com>, Juergen Gross <jgross@...e.com>, 
	"K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>, 
	Dexuan Cui <decui@...rosoft.com>, Ajay Kaher <ajay.kaher@...adcom.com>, 
	Jan Kiszka <jan.kiszka@...mens.com>, Andy Lutomirski <luto@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	John Stultz <jstultz@...gle.com>
Cc: linux-kernel@...r.kernel.org, linux-coco@...ts.linux.dev, 
	kvm@...r.kernel.org, virtualization@...ts.linux.dev, 
	linux-hyperv@...r.kernel.org, xen-devel@...ts.xenproject.org, 
	Tom Lendacky <thomas.lendacky@....com>, Nikunj A Dadhania <nikunj@....com>
Subject: [PATCH v2 16/38] x86/vmware: Nullify save/restore hooks when using
 VMware's sched_clock

Nullify the sched_clock save/restore hooks when using VMware's version of
sched_clock.  This will allow extending paravirt_set_sched_clock() to set
the save/restore hooks, without having to simultaneously change the
behavior of VMware guests.

Note, it's not at all obvious that it's safe/correct for VMware guests to
do nothing on suspend/resume, but that's a pre-existing problem.  Leave it
for a VMware expert to sort out.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kernel/cpu/vmware.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index d6f079a75f05..d6eadb5b37fd 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -344,8 +344,11 @@ static void __init vmware_paravirt_ops_setup(void)
 
 	vmware_cyc2ns_setup();
 
-	if (vmw_sched_clock)
+	if (vmw_sched_clock) {
 		paravirt_set_sched_clock(vmware_sched_clock);
+		x86_platform.save_sched_clock_state = NULL;
+		x86_platform.restore_sched_clock_state = NULL;
+	}
 
 	if (vmware_is_stealclock_available()) {
 		has_steal_clock = true;
-- 
2.48.1.711.g2feabab25a-goog