kvm: x86: use getboottime64 (87aeb54f) · Commits · 戴 / test

KVM reads the current boottime value as a struct timespec in order to calculate the guest wallclock time, resulting in an overflow in 2038 on 32-bit systems. The data then gets passed as an unsigned 32-bit number to the guest, and that in turn overflows in 2106. We cannot do much about the second overflow, which affects both 32-bit and 64-bit hosts, but we can ensure that they both behave the same way and don't overflow until 2106, by using getboottime64() to read a timespec64 value. Signed-off-by:

Arnd Bergmann <arnd@arndb.de> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -1165,7 +1165,7 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock)
		int version;
		int r;
		struct pvclock_wall_clock wc;
		struct timespec boot;
		struct timespec64 boot;

		if (!wall_clock)
		return;
		@@ -1188,13 +1188,13 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock)
		* wall clock specified here. guest system time equals host
		* system time for us, thus we must fill in host boot time here.
		*/
		getboottime(&boot);
		getboottime64(&boot);

		if (kvm->arch.kvmclock_offset) {
		struct timespec ts = ns_to_timespec(kvm->arch.kvmclock_offset);
		boot = timespec_sub(boot, ts);
		struct timespec64 ts = ns_to_timespec64(kvm->arch.kvmclock_offset);
		boot = timespec64_sub(boot, ts);
		}
		wc.sec = boot.tv_sec;
		wc.sec = (u32)boot.tv_sec; /* overflow in 2106 guest time */
		wc.nsec = boot.tv_nsec;
		wc.version = version;

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