KVM: x86/xen: update wallclock region

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>

1 files changed, 30 insertions, 3 deletions

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 924d4e853108..eab4dce93be1 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -21,15 +21,42 @@ DEFINE_STATIC_KEY_DEFERRED_FALSE(kvm_xen_enabled, HZ);
 
 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;
 	int idx = srcu_read_lock(&kvm->srcu);
 
 	ret = kvm_gfn_to_hva_cache_init(kvm, &kvm->arch.xen.shinfo_cache,
-					gfn_to_gpa(gfn), PAGE_SIZE);
-	if (!ret) {
-		kvm->arch.xen.shinfo_set = true;
+					gpa, PAGE_SIZE);
+	if (ret)
+		goto out;
+
+	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);
 
+out:
 	srcu_read_unlock(&kvm->srcu, idx);
 	return ret;
 }