The rework of the IDT setup changed the way how unused system gates are
accounted. At the end of the gate initialization all unused gates in the
system vector area are set to the spurios handler and marked as used for
consistency reasons.
Marking them as used breaks MS HyperV because it installs its hypercall
vector after that point and the installation is guarded by the bit in the
used_vectors map. So the hyperv vector stays directed to the spurious
interrupt handler.
Leave them marked as unused again and unbreak HyperV that way.
Fixes: dc20b2d52653 ("x86/idt: Move interrupt gate initialization to IDT code")
Reported-by: Stephen Hemminger <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
---
arch/x86/kernel/idt.c | 1 -
1 file changed, 1 deletion(-)
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -320,7 +320,6 @@ void __init idt_setup_apic_and_irq_gates
for_each_clear_bit_from(i, used_vectors, NR_VECTORS) {
#ifdef CONFIG_X86_LOCAL_APIC
- set_bit(i, used_vectors);
set_intr_gate(i, spurious_interrupt);
#else
entry = irq_entries_start + 8 * (i - FIRST_EXTERNAL_VECTOR);
> -----Original Message-----
> From: Thomas Gleixner [mailto:[email protected]]
> Sent: Friday, September 8, 2017 4:20 AM
> To: LKML <[email protected]>
> Cc: Stephen Hemminger <[email protected]>; Simon Xiao
> <[email protected]>; KY Srinivasan <[email protected]>; Haiyang Zhang
> <[email protected]>; Steven Rostedt <[email protected]>; Peter
> Zijlstra <[email protected]>; Linus Torvalds <torvalds@linux-
> foundation.org>; Josh Poimboeuf <[email protected]>; H. Peter Anvin
> <[email protected]>; Denys Vlasenko <[email protected]>; Brian Gerst
> <[email protected]>; Borislav Petkov <[email protected]>; Andy Lutomirski
> <[email protected]>
> Subject: [PATCH] x86/idt: Unbreak MS HyperV hypercall vector install
>
> The rework of the IDT setup changed the way how unused system gates are
> accounted. At the end of the gate initialization all unused gates in the
> system vector area are set to the spurios handler and marked as used for
> consistency reasons.
>
> Marking them as used breaks MS HyperV because it installs its hypercall
> vector after that point and the installation is guarded by the bit in
> the
> used_vectors map. So the hyperv vector stays directed to the spurious
> interrupt handler.
>
> Leave them marked as unused again and unbreak HyperV that way.
>
> Fixes: dc20b2d52653 ("x86/idt: Move interrupt gate initialization to IDT
> code")
> Reported-by: Stephen Hemminger <[email protected]>
> Signed-off-by: Thomas Gleixner <[email protected]>
Thanks for the quick response.
I tested the patch and the kernel boots up on Hyper-V now.
Reviewed-and-Tested-by: Haiyang Zhang <[email protected]>
On Fri, 8 Sep 2017 01:19:52 -0700
"Thomas Gleixner" <[email protected]> wrote:
> The rework of the IDT setup changed the way how unused system gates are
> accounted. At the end of the gate initialization all unused gates in the
> system vector area are set to the spurios handler and marked as used for
> consistency reasons.
>
> Marking them as used breaks MS HyperV because it installs its hypercall
> vector after that point and the installation is guarded by the bit in the
> used_vectors map. So the hyperv vector stays directed to the spurious
> interrupt handler.
>
> Leave them marked as unused again and unbreak HyperV that way.
>
> Fixes: dc20b2d52653 ("x86/idt: Move interrupt gate initialization to IDT
> code")
> Reported-by: Stephen Hemminger <[email protected]>
> Signed-off-by: Thomas Gleixner <[email protected]>
This fixes it, thanks.
Tested-by: Stephen Hemminger <[email protected]>
On Fri, 8 Sep 2017, Stephen Hemminger wrote:
> On Fri, 8 Sep 2017 01:19:52 -0700
> "Thomas Gleixner" <[email protected]> wrote:
>
> > The rework of the IDT setup changed the way how unused system gates are
> > accounted. At the end of the gate initialization all unused gates in the
> > system vector area are set to the spurios handler and marked as used for
> > consistency reasons.
> >
> > Marking them as used breaks MS HyperV because it installs its hypercall
> > vector after that point and the installation is guarded by the bit in the
> > used_vectors map. So the hyperv vector stays directed to the spurious
> > interrupt handler.
> >
> > Leave them marked as unused again and unbreak HyperV that way.
> >
> > Fixes: dc20b2d52653 ("x86/idt: Move interrupt gate initialization to IDT
> > code")
> > Reported-by: Stephen Hemminger <[email protected]>
> > Signed-off-by: Thomas Gleixner <[email protected]>
>
> This fixes it, thanks.
>
> Tested-by: Stephen Hemminger <[email protected]>
What's the reason that the vector is not set up early in the boot process?
Thanks,
tglx
> -----Original Message-----
> From: Thomas Gleixner [mailto:[email protected]]
> Sent: Friday, September 8, 2017 10:09 AM
> To: Stephen Hemminger <[email protected]>
> Cc: LKML <[email protected]>; Stephen Hemminger
> <[email protected]>; Simon Xiao <[email protected]>; KY
> Srinivasan <[email protected]>; Haiyang Zhang
> <[email protected]>; Steven Rostedt <[email protected]>; Peter
> Zijlstra <[email protected]>; Linus Torvalds <torvalds@linux-
> foundation.org>; Josh Poimboeuf <[email protected]>; H. Peter Anvin
> <[email protected]>; Denys Vlasenko <[email protected]>; Brian Gerst
> <[email protected]>; Borislav Petkov <[email protected]>; Andy Lutomirski
> <[email protected]>
> Subject: Re: [PATCH] x86/idt: Unbreak MS HyperV hypercall vector install
>
> On Fri, 8 Sep 2017, Stephen Hemminger wrote:
> > On Fri, 8 Sep 2017 01:19:52 -0700
> > "Thomas Gleixner" <[email protected]> wrote:
> >
> > > The rework of the IDT setup changed the way how unused system gates
> are
> > > accounted. At the end of the gate initialization all unused gates in the
> > > system vector area are set to the spurios handler and marked as used for
> > > consistency reasons.
> > >
> > > Marking them as used breaks MS HyperV because it installs its hypercall
> > > vector after that point and the installation is guarded by the bit in the
> > > used_vectors map. So the hyperv vector stays directed to the spurious
> > > interrupt handler.
> > >
> > > Leave them marked as unused again and unbreak HyperV that way.
> > >
> > > Fixes: dc20b2d52653 ("x86/idt: Move interrupt gate initialization to IDT
> > > code")
> > > Reported-by: Stephen Hemminger <[email protected]>
> > > Signed-off-by: Thomas Gleixner <[email protected]>
> >
> > This fixes it, thanks.
> >
> > Tested-by: Stephen Hemminger <[email protected]>
>
> What's the reason that the vector is not set up early in the boot process?
No specific reason other than that was the way I had coded it up initially. I will send in a patch to
fix that.
Regards,
K. Y
>
> Thanks,
>
> tglx
>