On 09/04/2014 02:42 PM, Paolo Bonzini wrote:
> Il 04/09/2014 21:15, Paolo Bonzini ha scritto:
>> Il 04/09/2014 20:16, Chris J Arges ha scritto:
>>>> +  boot_ns = timespec_to_ns(&tk->total_sleep_time)
>>>> +          + tk->wall_to_monotonic.tv_sec * (u64)NSEC_PER_SEC
>>>> +          + tk->wall_to_monotonic.tv_nsec
>>>> +          + tk->xtime_sec * (u64)NSEC_PER_SEC;
>>
>> So this means that the above 3.16-based code is not the same as
>>
>>         boot_ns = ktime_to_ns(ktime_add(tk->tkr.base_mono, tk->offs_boot));
>>
>> in 3.17.  Everything else in the patch you tested is the same as the
>> code that is in 3.17, so that's a start.
>>
>> Paolo
>>
> 
> Based on commit 02cba1598a2a3b689e79ad6dad2532521f638271 we have:
> 
>    offs_real - offs_boot = wall_to_monotonic + total_sleep_time
> 
> The patch I posted this morning separates tk->xtime_sec out of boot_ns, so
> all that is missing should be a change in boot_ns from base_mono + offs_boot
> to offs_real - offs_boot.
> 
> Chris, can you try this patch on top of the previous one:
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 92493e10937c..811eecc43fe8 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1031,7 +1031,7 @@ static void update_pvclock_gtod(struct timekeeper *tk)
>       struct pvclock_gtod_data *vdata = &pvclock_gtod_data;
>       u64 boot_ns;
>  
> -     boot_ns = ktime_to_ns(ktime_add(tk->tkr.base_mono, tk->offs_boot));
> +     boot_ns = ktime_to_ns(ktime_sub(tk->offs_real, tk->offs_boot));
>  
>       write_seqcount_begin(&vdata->seq);
> 
> If it doesn't work, then commit 02cba1598a2a3b689e79ad6dad2532521f638271
> is also broken.
> 
> Paolo
> 

Paolo,
That modification do your additional patch didn't work. However I was
able to modify the code as follows to get this test case working. The
only additional modification was:
+       vdata->nsec_base                = tk->xtime_sec * (u64)NSEC_PER_SEC
+                                       - boot_ns;

--chris j arges

--

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7b25aa2..60c0a9b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1023,8 +1023,8 @@ struct pvclock_gtod_data {
                u32     shift;
        } clock;

-       u64             boot_ns;
        u64             nsec_base;
+       u64             snsec_base;
 };

 static struct pvclock_gtod_data pvclock_gtod_data;
@@ -1034,7 +1034,7 @@ static void update_pvclock_gtod(struct timekeeper *tk)
        struct pvclock_gtod_data *vdata = &pvclock_gtod_data;
        u64 boot_ns;

-       boot_ns = ktime_to_ns(ktime_add(tk->tkr.base_mono, tk->offs_boot));
+       boot_ns = ktime_to_ns(ktime_sub(tk->offs_real, tk->offs_boot));

        write_seqcount_begin(&vdata->seq);

@@ -1045,8 +1045,9 @@ static void update_pvclock_gtod(struct timekeeper *tk)
        vdata->clock.mult               = tk->tkr.mult;
        vdata->clock.shift              = tk->tkr.shift;

-       vdata->boot_ns                  = boot_ns;
-       vdata->nsec_base                = tk->tkr.xtime_nsec;
+       vdata->nsec_base                = tk->xtime_sec * (u64)NSEC_PER_SEC
+                                       - boot_ns;
+       vdata->snsec_base               = tk->tkr.xtime_nsec;

        write_seqcount_end(&vdata->seq);
 }
@@ -1416,10 +1417,10 @@ static int do_monotonic_boot(s64 *t, cycle_t
*cycle_now)
        do {
                seq = read_seqcount_begin(&gtod->seq);
                mode = gtod->clock.vclock_mode;
-               ns = gtod->nsec_base;
+               ns = gtod->snsec_base;
                ns += vgettsc(cycle_now);
                ns >>= gtod->clock.shift;
-               ns += gtod->boot_ns;
+               ns += gtod->nsec_base;
        } while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
        *t = ns;
--
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