commit 8171cd68806b ("KVM: x86: use raw clock values consistently") causes KVM to accidentally write seconds to the nanoseconds field (and vice versa) in the KVM wall clock. Fix it by reversing this accidental switch. Modulo the written nanoseconds value by NSEC_PER_SEC to correct for the amount of time represented as seconds.
Fixes: 8171cd68806b ("KVM: x86: use raw clock values consistently") Cc: stable@vger.kernel.org Reviewed-by: Jim Mattson jmattson@google.com Reviewed-by: Peter Shier pshier@google.com Signed-off-by: Oliver Upton oupton@google.com --- Parent commit: c34b26b98cac ("KVM: MIPS: clean up redundant 'kvm_run' parameters")
arch/x86/kvm/x86.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e27d3db7e43f..86228cc6b29e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1809,8 +1809,9 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock) */ wall_nsec = ktime_get_real_ns() - get_kvmclock_ns(kvm);
- wc.nsec = do_div(wall_nsec, 1000000000); - wc.sec = (u32)wall_nsec; /* overflow in 2106 guest time */ + /* overflow in 2106 guest time */ + wc.sec = (u32)do_div(wall_nsec, NSEC_PER_SEC); + wc.nsec = wall_nsec % NSEC_PER_SEC; wc.version = version;
kvm_write_guest(kvm, wall_clock, &wc, sizeof(wc));
On Fri, Jul 24, 2020 at 10:35 AM Oliver Upton oupton@google.com wrote:
commit 8171cd68806b ("KVM: x86: use raw clock values consistently") causes KVM to accidentally write seconds to the nanoseconds field (and vice versa) in the KVM wall clock. Fix it by reversing this accidental switch. Modulo the written nanoseconds value by NSEC_PER_SEC to correct for the amount of time represented as seconds.
Fixes: 8171cd68806b ("KVM: x86: use raw clock values consistently") Cc: stable@vger.kernel.org Reviewed-by: Jim Mattson jmattson@google.com Reviewed-by: Peter Shier pshier@google.com Signed-off-by: Oliver Upton oupton@google.com
Parent commit: c34b26b98cac ("KVM: MIPS: clean up redundant 'kvm_run' parameters")
arch/x86/kvm/x86.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e27d3db7e43f..86228cc6b29e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1809,8 +1809,9 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock) */ wall_nsec = ktime_get_real_ns() - get_kvmclock_ns(kvm);
wc.nsec = do_div(wall_nsec, 1000000000);wc.sec = (u32)wall_nsec; /* overflow in 2106 guest time */
/* overflow in 2106 guest time */wc.sec = (u32)do_div(wall_nsec, NSEC_PER_SEC);wc.nsec = wall_nsec % NSEC_PER_SEC; wc.version = version; kvm_write_guest(kvm, wall_clock, &wc, sizeof(wc));-- 2.28.0.rc0.142.g3c755180ce-goog
Disregard, I crossed wires in my reading of do_div().
linux-stable-mirror@lists.linaro.org
-
Oliver Upton