Re: [PATCH v8 10/13] xen/arm: Resume memory management on Xen resume

[Mykola Kvach <xakep.amatop@xxxxxxxxx>]

Hi Volodymyr,

Thank you for the feedback.

On Fri, May 8, 2026 at 1:06 AM Volodymyr Babchuk
<Volodymyr_Babchuk@xxxxxxxx> wrote:
>
> Hi Mykola,
>
> Mykola Kvach <xakep.amatop@xxxxxxxxx> writes:
>
> > From: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
> >
> > The MMU must be enabled during the resume path before restoring context,
> > as virtual addresses are used to access the saved context data.
> >
>
> I agree with Luca, this patch does not makes sense as is. I don't see
> why it should be separated from the rest of the resume path that is
> added in the next patch

Ack. I'll combine this with the next patch in v9.

Best regards,
Mykola

>
> > This patch adds MMU setup during resume by reusing the existing
> > enable_secondary_cpu_mm function, which enables data cache and the MMU.
> > Before the MMU is enabled, the content of TTBR0_EL2 is changed to point
> > to init_ttbr (page tables used at runtime).
> >
> > Signed-off-by: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
> > Signed-off-by: Saeed Nowshadi <saeed.nowshadi@xxxxxxxxxx>
> > Signed-off-by: Mykyta Poturai <mykyta_poturai@xxxxxxxx>
> > Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx>
> > ---
> > Changes in v7:
> > - no functional changes, just moved commit
> > ---
> >  xen/arch/arm/arm64/head.S | 24 ++++++++++++++++++++++++
> >  1 file changed, 24 insertions(+)
> >
> > diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> > index 72c7b24498..596e960152 100644
> > --- a/xen/arch/arm/arm64/head.S
> > +++ b/xen/arch/arm/arm64/head.S
> > @@ -561,6 +561,30 @@ END(efi_xen_start)
> >
> >  #endif /* CONFIG_ARM_EFI */
> >
> > +#ifdef CONFIG_SYSTEM_SUSPEND
> > +
> > +FUNC(hyp_resume)
> > +        /* Initialize the UART if earlyprintk has been enabled. */
> > +#ifdef CONFIG_EARLY_PRINTK
> > +        bl    init_uart
> > +#endif
> > +        PRINT_ID("- Xen resuming -\r\n")
> > +
> > +        bl    check_cpu_mode
> > +        bl    cpu_init
> > +
> > +        ldr   x0, =start
> > +        adr   x20, start             /* x20 := paddr (start) */
> > +        sub   x20, x20, x0           /* x20 := phys-offset */
> > +        ldr   lr, =mmu_resumed
> > +        b     enable_secondary_cpu_mm
> > +
> > +mmu_resumed:
> > +        b .
> > +END(hyp_resume)
> > +
> > +#endif /* CONFIG_SYSTEM_SUSPEND */
> > +
> >  /*
> >   * Local variables:
> >   * mode: ASM
>
> --
> WBR, Volodymyr