| Message ID | 20180417060320.29090-1-ard.biesheuvel@linaro.org |
|---|---|
| State | Accepted |
| Commit | 411a373ed6426fb1bff253905b6a59ada44e18ad |
| Headers | show |
| Series | [edk2,v2] ArmPkg/TimerDxe: remove workaround for KVM timer handling | expand |
On 17 April 2018 at 08:03, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > When we first ported EDK2 to KVM/arm, we implemented a workaround for > the quirky timer handling on the KVM side. This has been fixed in > Linux commit f120cd6533d2 ("KVM: arm/arm64: timer: Allow the timer to > control the active state") dated 23 June 2014, which was incorporated > into Linux release 4.3. > > So almost 4 years later, it should be safe to drop this workaround on > the EDK2 side. > > This reverts commit b1a633434ddc. > > Cc: cross-distro@lists.linaro.org > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > Acked-by: Marc Zyngier <marc.zyngier@arm.com> > Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> > Acked-by: Laszlo Ersek <lersek@redhat.com> Pushed as 411a373ed6426fb1bff253905b6a59ada44e18ad Thanks all > --- > v2: add acks > > Note to cross-distro readers: this means guest firmware built with this patch > will not work on KVM/ARM hosts using kernel v4.2 or earlier. > > ArmPkg/Drivers/TimerDxe/TimerDxe.c | 1 - > ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c | 10 ---------- > 2 files changed, 11 deletions(-) > > diff --git a/ArmPkg/Drivers/TimerDxe/TimerDxe.c b/ArmPkg/Drivers/TimerDxe/TimerDxe.c > index a3202fa056f3..bd616d2efc73 100644 > --- a/ArmPkg/Drivers/TimerDxe/TimerDxe.c > +++ b/ArmPkg/Drivers/TimerDxe/TimerDxe.c > @@ -337,7 +337,6 @@ TimerInterruptHandler ( > > // Set next compare value > ArmGenericTimerSetCompareVal (CompareValue); > - ArmGenericTimerEnableTimer (); > ArmInstructionSynchronizationBarrier (); > } > > diff --git a/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c b/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c > index 69a4ceb62db6..c941895a3574 100644 > --- a/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c > +++ b/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c > @@ -26,16 +26,6 @@ ArmGenericTimerEnableTimer ( > > TimerCtrlReg = ArmReadCntvCtl (); > TimerCtrlReg |= ARM_ARCH_TIMER_ENABLE; > - > - // > - // When running under KVM, we need to unmask the interrupt on the timer side > - // as KVM will mask it when servicing the interrupt at the hypervisor level > - // and delivering the virtual timer interrupt to the guest. Otherwise, the > - // interrupt will fire again, trapping into the hypervisor again, etc. etc. > - // This is scheduled to be fixed on the KVM side, but there is no harm in > - // leaving this in once KVM gets fixed. > - // > - TimerCtrlReg &= ~ARM_ARCH_TIMER_IMASK; > ArmWriteCntvCtl (TimerCtrlReg); > } > > -- > 2.17.0 > _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
Hi Ard, Sorry for the late reply. On 19/04/18 09:16, Ard Biesheuvel wrote: > On 17 April 2018 at 08:03, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: >> When we first ported EDK2 to KVM/arm, we implemented a workaround for >> the quirky timer handling on the KVM side. This has been fixed in >> Linux commit f120cd6533d2 ("KVM: arm/arm64: timer: Allow the timer to >> control the active state") dated 23 June 2014, which was incorporated >> into Linux release 4.3. >> >> So almost 4 years later, it should be safe to drop this workaround on >> the EDK2 side. >> >> This reverts commit b1a633434ddc. >> >> Cc: cross-distro@lists.linaro.org >> Contributed-under: TianoCore Contribution Agreement 1.1 >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> Acked-by: Marc Zyngier <marc.zyngier@arm.com> >> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> >> Acked-by: Laszlo Ersek <lersek@redhat.com> > > Pushed as 411a373ed6426fb1bff253905b6a59ada44e18ad While this was added for KVM, I believe that code is also needed by Xen. Indeed before injecting the interrupt the hypervisor will mask the interrupt. So would it be possible to revert that patch? Cheers, > > Thanks all > >> --- >> v2: add acks >> >> Note to cross-distro readers: this means guest firmware built with this patch >> will not work on KVM/ARM hosts using kernel v4.2 or earlier. >> >> ArmPkg/Drivers/TimerDxe/TimerDxe.c | 1 - >> ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c | 10 ---------- >> 2 files changed, 11 deletions(-) >> >> diff --git a/ArmPkg/Drivers/TimerDxe/TimerDxe.c b/ArmPkg/Drivers/TimerDxe/TimerDxe.c >> index a3202fa056f3..bd616d2efc73 100644 >> --- a/ArmPkg/Drivers/TimerDxe/TimerDxe.c >> +++ b/ArmPkg/Drivers/TimerDxe/TimerDxe.c >> @@ -337,7 +337,6 @@ TimerInterruptHandler ( >> >> // Set next compare value >> ArmGenericTimerSetCompareVal (CompareValue); >> - ArmGenericTimerEnableTimer (); >> ArmInstructionSynchronizationBarrier (); >> } >> >> diff --git a/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c b/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c >> index 69a4ceb62db6..c941895a3574 100644 >> --- a/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c >> +++ b/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c >> @@ -26,16 +26,6 @@ ArmGenericTimerEnableTimer ( >> >> TimerCtrlReg = ArmReadCntvCtl (); >> TimerCtrlReg |= ARM_ARCH_TIMER_ENABLE; >> - >> - // >> - // When running under KVM, we need to unmask the interrupt on the timer side >> - // as KVM will mask it when servicing the interrupt at the hypervisor level >> - // and delivering the virtual timer interrupt to the guest. Otherwise, the >> - // interrupt will fire again, trapping into the hypervisor again, etc. etc. >> - // This is scheduled to be fixed on the KVM side, but there is no harm in >> - // leaving this in once KVM gets fixed. >> - // >> - TimerCtrlReg &= ~ARM_ARCH_TIMER_IMASK; >> ArmWriteCntvCtl (TimerCtrlReg); >> } >> >> -- >> 2.17.0 >> > _______________________________________________ > cross-distro mailing list > cross-distro@lists.linaro.org > https://lists.linaro.org/mailman/listinfo/cross-distro > -- Julien Grall _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
On 19 April 2018 at 16:23, Julien Grall <julien.grall@arm.com> wrote: > Hi Ard, > > Sorry for the late reply. > > On 19/04/18 09:16, Ard Biesheuvel wrote: >> >> On 17 April 2018 at 08:03, Ard Biesheuvel <ard.biesheuvel@linaro.org> >> wrote: >>> >>> When we first ported EDK2 to KVM/arm, we implemented a workaround for >>> the quirky timer handling on the KVM side. This has been fixed in >>> Linux commit f120cd6533d2 ("KVM: arm/arm64: timer: Allow the timer to >>> control the active state") dated 23 June 2014, which was incorporated >>> into Linux release 4.3. >>> >>> So almost 4 years later, it should be safe to drop this workaround on >>> the EDK2 side. >>> >>> This reverts commit b1a633434ddc. >>> >>> Cc: cross-distro@lists.linaro.org >>> Contributed-under: TianoCore Contribution Agreement 1.1 >>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> >>> Acked-by: Marc Zyngier <marc.zyngier@arm.com> >>> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> >>> Acked-by: Laszlo Ersek <lersek@redhat.com> >> >> >> Pushed as 411a373ed6426fb1bff253905b6a59ada44e18ad > > > While this was added for KVM, I believe that code is also needed by Xen. > Indeed before injecting the interrupt the hypervisor will mask the > interrupt. > > So would it be possible to revert that patch? > Given that this is now a Xen-only quirk, I'd rather work around it by creating a separate ArmGenericTimerCounterLib implementation for Xen. I will try to put something together beginning of next week. _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
On 19/04/18 15:34, Ard Biesheuvel wrote: > On 19 April 2018 at 16:23, Julien Grall <julien.grall@arm.com> wrote: >> Hi Ard, >> >> Sorry for the late reply. >> >> On 19/04/18 09:16, Ard Biesheuvel wrote: >>> >>> On 17 April 2018 at 08:03, Ard Biesheuvel <ard.biesheuvel@linaro.org> >>> wrote: >>>> >>>> When we first ported EDK2 to KVM/arm, we implemented a workaround for >>>> the quirky timer handling on the KVM side. This has been fixed in >>>> Linux commit f120cd6533d2 ("KVM: arm/arm64: timer: Allow the timer to >>>> control the active state") dated 23 June 2014, which was incorporated >>>> into Linux release 4.3. >>>> >>>> So almost 4 years later, it should be safe to drop this workaround on >>>> the EDK2 side. >>>> >>>> This reverts commit b1a633434ddc. >>>> >>>> Cc: cross-distro@lists.linaro.org >>>> Contributed-under: TianoCore Contribution Agreement 1.1 >>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> >>>> Acked-by: Marc Zyngier <marc.zyngier@arm.com> >>>> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> >>>> Acked-by: Laszlo Ersek <lersek@redhat.com> >>> >>> >>> Pushed as 411a373ed6426fb1bff253905b6a59ada44e18ad >> >> >> While this was added for KVM, I believe that code is also needed by Xen. >> Indeed before injecting the interrupt the hypervisor will mask the >> interrupt. >> >> So would it be possible to revert that patch? >> > > Given that this is now a Xen-only quirk, I'd rather work around it by > creating a separate ArmGenericTimerCounterLib implementation for Xen. That would work for me. > > I will try to put something together beginning of next week. I am happy to test it. Cheers, -- Julien Grall _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
diff --git a/ArmPkg/Drivers/TimerDxe/TimerDxe.c b/ArmPkg/Drivers/TimerDxe/TimerDxe.c index a3202fa056f3..bd616d2efc73 100644 --- a/ArmPkg/Drivers/TimerDxe/TimerDxe.c +++ b/ArmPkg/Drivers/TimerDxe/TimerDxe.c @@ -337,7 +337,6 @@ TimerInterruptHandler ( // Set next compare value ArmGenericTimerSetCompareVal (CompareValue); - ArmGenericTimerEnableTimer (); ArmInstructionSynchronizationBarrier (); } diff --git a/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c b/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c index 69a4ceb62db6..c941895a3574 100644 --- a/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c +++ b/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c @@ -26,16 +26,6 @@ ArmGenericTimerEnableTimer ( TimerCtrlReg = ArmReadCntvCtl (); TimerCtrlReg |= ARM_ARCH_TIMER_ENABLE; - - // - // When running under KVM, we need to unmask the interrupt on the timer side - // as KVM will mask it when servicing the interrupt at the hypervisor level - // and delivering the virtual timer interrupt to the guest. Otherwise, the - // interrupt will fire again, trapping into the hypervisor again, etc. etc. - // This is scheduled to be fixed on the KVM side, but there is no harm in - // leaving this in once KVM gets fixed. - // - TimerCtrlReg &= ~ARM_ARCH_TIMER_IMASK; ArmWriteCntvCtl (TimerCtrlReg); }
When we first ported EDK2 to KVM/arm, we implemented a workaround for the quirky timer handling on the KVM side. This has been fixed in Linux commit f120cd6533d2 ("KVM: arm/arm64: timer: Allow the timer to control the active state") dated 23 June 2014, which was incorporated into Linux release 4.3. So almost 4 years later, it should be safe to drop this workaround on the EDK2 side. This reverts commit b1a633434ddc. Cc: cross-distro@lists.linaro.org Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> Acked-by: Laszlo Ersek <lersek@redhat.com> --- v2: add acks Note to cross-distro readers: this means guest firmware built with this patch will not work on KVM/ARM hosts using kernel v4.2 or earlier. ArmPkg/Drivers/TimerDxe/TimerDxe.c | 1 - ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c | 10 ---------- 2 files changed, 11 deletions(-) -- 2.17.0 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel