[PATCH v5 09/16] KVM: x86/xen: update wallclock region

[David Woodhouse <dwmw2@infradead.org>]

From: Joao Martins <joao.m.martins@oracle.com>

Wallclock on Xen is written in the shared_info page.

To that purpose, export kvm_write_wall_clock() and pass on the GPA of
its location to populate the shared_info wall clock data.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 arch/x86/kvm/x86.c | 17 ++++++++++++-----
 arch/x86/kvm/x86.h |  1 +
 arch/x86/kvm/xen.c | 28 +++++++++++++++++++++++++++-
 3 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fd0a4ff1157e..0cdebdcaa4c2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1927,15 +1927,14 @@ static s64 get_kvmclock_base_ns(void)
 }
 #endif
 
-static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock)
+void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock, int sec_hi_ofs)
 {
 	int version;
 	int r;
 	struct pvclock_wall_clock wc;
+	u32 wc_sec_hi;
 	u64 wall_nsec;
 
-	kvm->arch.wall_clock = wall_clock;
-
 	if (!wall_clock)
 		return;
 
@@ -1964,6 +1963,12 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock)
 
 	kvm_write_guest(kvm, wall_clock, &wc, sizeof(wc));
 
+	if (sec_hi_ofs) {
+		wc_sec_hi = wall_nsec >> 32;
+		kvm_write_guest(kvm, wall_clock + sec_hi_ofs,
+				&wc_sec_hi, sizeof(wc_sec_hi));
+	}
+
 	version++;
 	kvm_write_guest(kvm, wall_clock, &version, sizeof(version));
 }
@@ -3121,13 +3126,15 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE2))
 			return 1;
 
-		kvm_write_wall_clock(vcpu->kvm, data);
+		vcpu->kvm->arch.wall_clock = data;
+		kvm_write_wall_clock(vcpu->kvm, data, 0);
 		break;
 	case MSR_KVM_WALL_CLOCK:
 		if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE))
 			return 1;
 
-		kvm_write_wall_clock(vcpu->kvm, data);
+		vcpu->kvm->arch.wall_clock = data;
+		kvm_write_wall_clock(vcpu->kvm, data, 0);
 		break;
 	case MSR_KVM_SYSTEM_TIME_NEW:
 		if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE2))
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index c5ee0f5ce0f1..8982a7bf2041 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -247,6 +247,7 @@ static inline bool kvm_vcpu_latch_init(struct kvm_vcpu *vcpu)
 	return is_smm(vcpu) || kvm_x86_ops.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);
 
 void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr);
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 9dd9c42842b8..e5117a611737 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -19,14 +19,40 @@
 
 static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
 {
+	gpa_t gpa = gfn_to_gpa(gfn);
+	int wc_ofs, sec_hi_ofs;
 	int ret;
 
 	ret = kvm_gfn_to_hva_cache_init(kvm, &kvm->arch.xen.shinfo_cache,
-					gfn_to_gpa(gfn), PAGE_SIZE);
+					gpa, PAGE_SIZE);
 	if (ret)
 		return ret;
 
 	kvm->arch.xen.shinfo_set = true;
+
+	/* Paranoia checks on the 32-bit struct layout */
+	BUILD_BUG_ON(offsetof(struct compat_shared_info, wc) != 0x900);
+	BUILD_BUG_ON(offsetof(struct compat_shared_info, arch.wc_sec_hi) != 0x924);
+	BUILD_BUG_ON(offsetof(struct pvclock_vcpu_time_info, version) != 0);
+
+	/* 32-bit location by default */
+	wc_ofs = offsetof(struct compat_shared_info, wc);
+	sec_hi_ofs = offsetof(struct compat_shared_info, arch.wc_sec_hi);
+
+#ifdef CONFIG_X86_64
+	/* Paranoia checks on the 64-bit struct layout */
+	BUILD_BUG_ON(offsetof(struct shared_info, wc) != 0xc00);
+	BUILD_BUG_ON(offsetof(struct shared_info, wc_sec_hi) != 0xc0c);
+
+	if (kvm->arch.xen.long_mode) {
+		wc_ofs = offsetof(struct shared_info, wc);
+		sec_hi_ofs = offsetof(struct shared_info, wc_sec_hi);
+	}
+#endif
+
+	kvm_write_wall_clock(kvm, gpa + wc_ofs, sec_hi_ofs - wc_ofs);
+	kvm_make_all_cpus_request(kvm, KVM_REQ_MASTERCLOCK_UPDATE);
+
 	return 0;
 }
 
-- 
2.29.2