[PATCH] KVM: arm64: Move __hyp_set_vectors out of .hyp.text

[PATCH] KVM: arm64: Move __hyp_set_vectors out of .hyp.text

[Quentin Perret]

The .hyp.text section is supposed to be reserved for the nVHE EL2 code.
However, there is currently one occurrence of EL1 executing code located
in .hyp.text when calling __hyp_{re}set_vectors(), which happen to sit
next to the EL2 stub vectors. While not a problem yet, such patterns
will cause issues when removing the host kernel from the TCB, so a
cleaner split would be preferable.

Fix this by delimiting the end of the .hyp.text section in hyp-stub.S.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kernel/hyp-stub.S | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
index 160f5881a0b7..8a60f9c586bb 100644
--- a/arch/arm64/kernel/hyp-stub.S
+++ b/arch/arm64/kernel/hyp-stub.S
@@ -85,6 +85,8 @@ SYM_CODE_END(\label)
 	invalid_vector	el1_fiq_invalid
 	invalid_vector	el1_error_invalid
 
+	.popsection
+
 /*
  * __hyp_set_vectors: Call this after boot to set the initial hypervisor
  * vectors as part of hypervisor installation.  On an SMP system, this should
-- 
2.30.0.280.ga3ce27912f-goog

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Re: [PATCH] KVM: arm64: Move __hyp_set_vectors out of .hyp.text

[Marc Zyngier]

On 2021-01-28 17:38, Quentin Perret wrote:
> The .hyp.text section is supposed to be reserved for the nVHE EL2 code.
> However, there is currently one occurrence of EL1 executing code 
> located
> in .hyp.text when calling __hyp_{re}set_vectors(), which happen to sit
> next to the EL2 stub vectors. While not a problem yet, such patterns
> will cause issues when removing the host kernel from the TCB, so a
> cleaner split would be preferable.
> 
> Fix this by delimiting the end of the .hyp.text section in hyp-stub.S.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/kernel/hyp-stub.S | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm64/kernel/hyp-stub.S 
> b/arch/arm64/kernel/hyp-stub.S
> index 160f5881a0b7..8a60f9c586bb 100644
> --- a/arch/arm64/kernel/hyp-stub.S
> +++ b/arch/arm64/kernel/hyp-stub.S
> @@ -85,6 +85,8 @@ SYM_CODE_END(\label)
>  	invalid_vector	el1_fiq_invalid
>  	invalid_vector	el1_error_invalid
> 
> +	.popsection
> +
>  /*
>   * __hyp_set_vectors: Call this after boot to set the initial 
> hypervisor
>   * vectors as part of hypervisor installation.  On an SMP system, this 
> should

Thanks for tracking this one down, Quentin.

Catalin, Will: should you want to take this one via the arm64 tree,
please add my

Acked-by: Marc Zyngier <maz:kernel.org>

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...
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Re: [PATCH] KVM: arm64: Move __hyp_set_vectors out of .hyp.text

[Will Deacon]

On Thu, Jan 28, 2021 at 06:11:52PM +0000, Marc Zyngier wrote:
> On 2021-01-28 17:38, Quentin Perret wrote:
> > The .hyp.text section is supposed to be reserved for the nVHE EL2 code.
> > However, there is currently one occurrence of EL1 executing code located
> > in .hyp.text when calling __hyp_{re}set_vectors(), which happen to sit
> > next to the EL2 stub vectors. While not a problem yet, such patterns
> > will cause issues when removing the host kernel from the TCB, so a
> > cleaner split would be preferable.
> > 
> > Fix this by delimiting the end of the .hyp.text section in hyp-stub.S.
> > 
> > Signed-off-by: Quentin Perret <qperret@google.com>
> > ---
> >  arch/arm64/kernel/hyp-stub.S | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
> > index 160f5881a0b7..8a60f9c586bb 100644
> > --- a/arch/arm64/kernel/hyp-stub.S
> > +++ b/arch/arm64/kernel/hyp-stub.S
> > @@ -85,6 +85,8 @@ SYM_CODE_END(\label)
> >  	invalid_vector	el1_fiq_invalid
> >  	invalid_vector	el1_error_invalid
> > 
> > +	.popsection
> > +
> >  /*
> >   * __hyp_set_vectors: Call this after boot to set the initial
> > hypervisor
> >   * vectors as part of hypervisor installation.  On an SMP system, this
> > should
> 
> Thanks for tracking this one down, Quentin.
> 
> Catalin, Will: should you want to take this one via the arm64 tree,
> please add my
> 
> Acked-by: Marc Zyngier <maz:kernel.org>

Cheers, I'll pick this up for 5.12 with your Ack.

Will
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Re: [PATCH] KVM: arm64: Move __hyp_set_vectors out of .hyp.text

[Will Deacon]

On Thu, 28 Jan 2021 17:38:50 +0000, Quentin Perret wrote:
> The .hyp.text section is supposed to be reserved for the nVHE EL2 code.
> However, there is currently one occurrence of EL1 executing code located
> in .hyp.text when calling __hyp_{re}set_vectors(), which happen to sit
> next to the EL2 stub vectors. While not a problem yet, such patterns
> will cause issues when removing the host kernel from the TCB, so a
> cleaner split would be preferable.
> 
> [...]

Applied to arm64 (for-next/misc), thanks!

[1/1] KVM: arm64: Move __hyp_set_vectors out of .hyp.text
      https://git.kernel.org/arm64/c/e30be1455bd3

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
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