Re: [PATCH 1/1] drivers/hv: correct tsc page sequence invalid value

[Denis V. Lunev]

On 11/12/2015 08:35 PM, KY Srinivasan wrote:
> > -----Original Message-----
> > From: Denis V. Lunev [mailto:den@xxxxxxxxxx]
> > Sent: Wednesday, November 11, 2015 11:16 PM
> > To: KY Srinivasan <kys@xxxxxxxxxxxxx>
> > Cc: rkagan@xxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; Andrey Smetanin <asmetanin@xxxxxxxxxxxxx>;
> > Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; Vitaly Kuznetsov
> > <vkuznets@xxxxxxxxxx>
> > Subject: Re: [PATCH 1/1] drivers/hv: correct tsc page sequence invalid value
> >
> > On 11/02/2015 10:42 PM, KY Srinivasan wrote:
> > > > -----Original Message-----
> > > > From: Denis V. Lunev [mailto:den@xxxxxxxxxx]
> > > > Sent: Monday, November 2, 2015 3:34 AM
> > > > Cc: rkagan@xxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; linux-
> > > > kernel@xxxxxxxxxxxxxxx; Andrey Smetanin <asmetanin@xxxxxxxxxxxxx>;
> > KY
> > > > Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang Zhang
> > > > <haiyangz@xxxxxxxxxxxxx>; Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>;
> > > > Denis V. Lunev <den@xxxxxxxxxx>
> > > > Subject: [PATCH 1/1] drivers/hv: correct tsc page sequence invalid value
> > > >
> > > > From: Andrey Smetanin <asmetanin@xxxxxxxxxxxxx>
> > > >
> > > > Hypervisor Top Level Functional Specification v3/4 says
> > > > that TSC page sequence value = -1(0xFFFFFFFF) is used to
> > > > indicate that TSC page no longer reliable source of reference
> > > > timer. Unfortunately, we found that Windows Hyper-V guest
> > > > side implementation uses sequence value = 0 to indicate
> > > > that Tsc page no longer valid. This is clearly visible
> > > > inside Windows 2012R2 ntoskrnl.exe HvlGetReferenceTime()
> > > > function dissassembly:
> > > >
> > > > HvlGetReferenceTime proc near
> > > >                    xchg    ax, ax
> > > > loc_1401C3132:
> > > >                    mov     rax, cs:HvlpReferenceTscPage
> > > >                    mov     r9d, [rax]
> > > >                    test    r9d, r9d
> > > >                    jz      short loc_1401C3176
> > > >                    rdtsc
> > > >                    mov     rcx, cs:HvlpReferenceTscPage
> > > >                    shl     rdx, 20h
> > > >                    or      rdx, rax
> > > >                    mov     rax, [rcx+8]
> > > >                    mov     rcx, cs:HvlpReferenceTscPage
> > > >                    mov     r8, [rcx+10h]
> > > >                    mul     rdx
> > > >                    mov     rax, cs:HvlpReferenceTscPage
> > > >                    add     rdx, r8
> > > >                    mov     ecx, [rax]
> > > >                    cmp     ecx, r9d
> > > >                    jnz     short loc_1401C3132
> > > >                    jmp     short loc_1401C3184
> > > > loc_1401C3176:
> > > >                    mov     ecx, 40000020h
> > > >                    rdmsr
> > > >                    shl     rdx, 20h
> > > >                    or      rdx, rax
> > > > loc_1401C3184:
> > > >                    mov     rax, rdx
> > > >                    retn
> > > > HvlGetReferenceTime endp
> > > >
> > > > This patch aligns Tsc page invalid sequence value with
> > > > Windows Hyper-V guest implementation which is more
> > > > compatible with both Hyper-V hypervisor and KVM hypervisor.
> > > >
> > > > Signed-off-by: Andrey Smetanin <asmetanin@xxxxxxxxxxxxx>
> > > > CC: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
> > > Thanks Andrey; the Hyper-V team will be updating the Hyper-V
> > documentation.
> > > Acked-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> > >
> > > Regards,
> > >
> > > K. Y
> > K.Y.,
> >
> > can you pls clarify the state of this patch? It is a bit unclear
> > to me whether it is applied or not.
> I will be submitting this shortly.
>
> > By the way, I also do not see the following patch
> > "drivers/hv: cleanup synic msrs if vmbus connect failed"
> > as applied in the Linux-next. You have promised to resend
> > it will correct author.
> It was resent on October 29. It is in Greg's queue.
>
> Regards,
>
> K. Y
> > Thank you in advance,
> >       Den
thank you very much for this update :)

Den
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