Hi, > On Oct 6, 2023, at 06:53, Stefano Stabellini <[email protected]> wrote: > > On Thu, 5 Oct 2023, Julien Grall wrote: >> From: Julien Grall <[email protected]> >> >> Per ACPI 6.5 section 5.2.25 ("Generic Timer Description Table (GTDT)"), >> the fields "Secure EL1 Timer GSIV/Flags" are optional and an OS running >> in non-secure world is meant to ignore the values. >> >> However, Xen is trying to reserve the value. When booting on Graviton >> 2 metal instances, this would result to crash a boot because the >> value is 0 which is already reserved (I haven't checked for which device). >> While nothing prevent a PPI to be shared, the field should have been >> ignored by Xen. >> >> For the Device-Tree case, I couldn't find a statement suggesting >> that the secure physical timer interrupt is ignored. In fact, I have >> found some code in Linux using it as a fallback. That said, it should >> never be used. >> >> As I am not aware of any issue when booting using Device-Tree, the >> physical timer interrupt is only ignored for ACPI. >> >> Signed-off-by: Julien Grall <[email protected]> >> >> ---- >> >> This has not been tested on Graviton 2 because I can't seem to get >> the serial console working properly. @Dan would you be able to try it? >> >> It would also be good to understand why 0 why already reserved. This >> may be a sign for other issues in the ACPI code. >> --- >> xen/arch/arm/time.c | 4 ---- >> xen/arch/arm/vtimer.c | 17 +++++++++++++++-- >> 2 files changed, 15 insertions(+), 6 deletions(-) >> >> diff --git a/xen/arch/arm/time.c b/xen/arch/arm/time.c >> index 3535bd8ac7c7..8fc14cd3ff62 100644 >> --- a/xen/arch/arm/time.c >> +++ b/xen/arch/arm/time.c >> @@ -78,10 +78,6 @@ static int __init arch_timer_acpi_init(struct >> acpi_table_header *header) >> irq_set_type(gtdt->non_secure_el1_interrupt, irq_type); >> timer_irq[TIMER_PHYS_NONSECURE_PPI] = gtdt->non_secure_el1_interrupt; >> >> - irq_type = acpi_get_timer_irq_type(gtdt->secure_el1_flags); >> - irq_set_type(gtdt->secure_el1_interrupt, irq_type); >> - timer_irq[TIMER_PHYS_SECURE_PPI] = gtdt->secure_el1_interrupt; >> - >> irq_type = acpi_get_timer_irq_type(gtdt->virtual_timer_flags); >> irq_set_type(gtdt->virtual_timer_interrupt, irq_type); >> timer_irq[TIMER_VIRT_PPI] = gtdt->virtual_timer_interrupt; >> diff --git a/xen/arch/arm/vtimer.c b/xen/arch/arm/vtimer.c >> index c54360e20266..e73ae33c1b58 100644 >> --- a/xen/arch/arm/vtimer.c >> +++ b/xen/arch/arm/vtimer.c >> @@ -8,6 +8,7 @@ >> * Copyright (c) 2011 Citrix Systems. >> */ >> >> +#include <xen/acpi.h> >> #include <xen/lib.h> >> #include <xen/perfc.h> >> #include <xen/sched.h> >> @@ -61,10 +62,22 @@ int domain_vtimer_init(struct domain *d, struct >> xen_arch_domainconfig *config) >> >> config->clock_frequency = timer_dt_clock_frequency; >> >> - /* At this stage vgic_reserve_virq can't fail */ >> + /* >> + * Per the ACPI specification, providing a secure EL1 timer >> + * interrupt is optional and will be ignored by non-secure OS. >> + * Therefore don't reserve the interrupt number for the HW domain >> + * and ACPI. >> + * >> + * Note that we should still reserve it when using the Device-Tree >> + * because the interrupt is not optional. That said, we are not >> + * expecting any OS to use it when running on top of Xen. >> + * >> + * At this stage vgic_reserve_virq() is not meant to fail. >> + */ > > NIT: minor code style issue that can be solved on commit > > Assuming it passes Dan's test: > > Reviewed-by: Stefano Stabellini <[email protected]>
Release-acked-by: Henry Wang <[email protected]> Kind regards, Henry > > >> if ( is_hardware_domain(d) ) >> { >> - if ( !vgic_reserve_virq(d, timer_get_irq(TIMER_PHYS_SECURE_PPI)) ) >> + if ( acpi_disabled && >> + !vgic_reserve_virq(d, timer_get_irq(TIMER_PHYS_SECURE_PPI)) ) >> BUG(); >> >> if ( !vgic_reserve_virq(d, timer_get_irq(TIMER_PHYS_NONSECURE_PPI)) ) >> -- >> 2.40.1 >>
