| Message ID | 20180315102826.10517-1-ard.biesheuvel@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [edk2] ArmPkg/TimerDxe: remove workaround for KVM timer handling | expand |
On 15/03/18 10:28, Ard Biesheuvel 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. > > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > --- > 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); > } > > Acked-by: Marc Zyngier <marc.zyngier@arm.com> M. -- Jazz is not dead. It just smells funny... _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
On Thu, Mar 15, 2018 at 10:28:26AM +0000, Ard Biesheuvel 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. > > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> I'm happy with this, with Marc's Ack. Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> However, if this can affect old kernels running in vms, could you ping cross-distro@lists.linaro.org as well, so it doesn't catch anyone by surprise? / Leif > --- > 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); > } > > -- > 2.15.1 > _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
On 03/15/18 20:01, Leif Lindholm wrote: > On Thu, Mar 15, 2018 at 10:28:26AM +0000, Ard Biesheuvel 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. >> >> Contributed-under: TianoCore Contribution Agreement 1.1 >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > I'm happy with this, with Marc's Ack. > Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> > > However, if this can affect old kernels running in vms, could you ping > cross-distro@lists.linaro.org as well, so it doesn't catch anyone by > surprise? If I understand correctly, the patch could negatively affect old kernels that run on *hosts*. (Discounting nested virtualization, which I'm perfectly willing to ignore for this discussion.) Emailing the cross-distro list shouldn't hurt in any case. From my side (since I was CC'd): Acked-by: Laszlo Ersek <lersek@redhat.com> Thanks! Laszlo > > / > Leif > >> --- >> 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); >> } >> >> -- >> 2.15.1 >> _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
On 15 March 2018 at 19:01, Leif Lindholm <leif.lindholm@linaro.org> wrote: > On Thu, Mar 15, 2018 at 10:28:26AM +0000, Ard Biesheuvel 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. >> >> Contributed-under: TianoCore Contribution Agreement 1.1 >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > I'm happy with this, with Marc's Ack. > Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> > > However, if this can affect old kernels running in vms, could you ping > cross-distro@lists.linaro.org as well, so it doesn't catch anyone by > surprise? > It will affects VMs running new firmware on ancient host kernels (and v4.2 *is* ancient when it comes to KVM/arm64 and server stuff imo) >> --- >> 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); >> } >> >> -- >> 2.15.1 >> _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
On Fri, Mar 16, 2018 at 11:28:21AM +0000, Ard Biesheuvel wrote: > On 15 March 2018 at 19:01, Leif Lindholm <leif.lindholm@linaro.org> wrote: > > On Thu, Mar 15, 2018 at 10:28:26AM +0000, Ard Biesheuvel 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. > >> > >> Contributed-under: TianoCore Contribution Agreement 1.1 > >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > > > I'm happy with this, with Marc's Ack. > > Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> > > > > However, if this can affect old kernels running in vms, could you ping > > cross-distro@lists.linaro.org as well, so it doesn't catch anyone by > > surprise? > > It will affects VMs running new firmware on ancient host kernels (and > v4.2 *is* ancient when it comes to KVM/arm64 and server stuff imo) Oh, it is, but if we have https://bugs.launchpad.net/ubuntu/+source/edk2/+bug/1744754 (Xenial guest), imagining people running a Zesty host isn't that much more of a stretch (it's only EOL 2 months ago). / Leif > >> --- > >> 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); > >> } > >> > >> -- > >> 2.15.1 > >> _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
On 16 March 2018 at 11:46, Leif Lindholm <leif.lindholm@linaro.org> wrote: > On Fri, Mar 16, 2018 at 11:28:21AM +0000, Ard Biesheuvel wrote: >> On 15 March 2018 at 19:01, Leif Lindholm <leif.lindholm@linaro.org> wrote: >> > On Thu, Mar 15, 2018 at 10:28:26AM +0000, Ard Biesheuvel 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. >> >> >> >> Contributed-under: TianoCore Contribution Agreement 1.1 >> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> > >> > I'm happy with this, with Marc's Ack. >> > Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> >> > >> > However, if this can affect old kernels running in vms, could you ping >> > cross-distro@lists.linaro.org as well, so it doesn't catch anyone by >> > surprise? >> >> It will affects VMs running new firmware on ancient host kernels (and >> v4.2 *is* ancient when it comes to KVM/arm64 and server stuff imo) > > Oh, it is, but if we have > https://bugs.launchpad.net/ubuntu/+source/edk2/+bug/1744754 > (Xenial guest), imagining people running a Zesty host isn't that much > more of a stretch (it's only EOL 2 months ago). > Xenial has v4.4, Zesty has v4.10, if I am not mistaken? Still doesn't hurt to cc cross-distro, obviously. Just sayin' _______________________________________________ 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. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- ArmPkg/Drivers/TimerDxe/TimerDxe.c | 1 - ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c | 10 ---------- 2 files changed, 11 deletions(-) -- 2.15.1 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel