KVM: x86: Fix wall clock writes in Xen shared_info not to mark page dirty

When dirty ring logging is enabled, any dirty logging without an active
vCPU context will cause a kernel oops. But we've already declared that
the shared_info page doesn't get dirty tracking anyway, since it would
be kind of insane to mark it dirty every time we deliver an event channel
interrupt. Userspace is supposed to just assume it's always dirty any
time a vCPU can run or event channels are routed.

So stop using the generic kvm_write_wall_clock() and just write directly
through the gfn_to_pfn_cache that we already have set up.

We can make kvm_write_wall_clock() static in x86.c again now, but let's
not remove the 'sec_hi_ofs' argument even though it's not used yet. At
some point we *will* want to use that for KVM guests too.

Fixes: 629b5348841a ("KVM: x86/xen: update wallclock region")
Reported-by: butt3rflyh4ck <butterflyhuangxx@gmail.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20211210163625.2886-6-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 4abcd8d9836d..da7031e80f23 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -301,7 +301,6 @@ static inline bool kvm_vcpu_latch_init(struct kvm_vcpu *vcpu)
 	return is_smm(vcpu) || static_call(kvm_x86_apic_init_signal_blocked)(vcpu);
 }
 
-void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock, int sec_hi_ofs);
 void kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip);
 
 u64 get_kvmclock_ns(struct kvm *kvm);