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  • Florian Mayer Florian Mayer fmayer
1 author
  1. Oct 31, 2013
  3. Oct 20, 2013
  5. Oct 17, 2013
  7. Oct 14, 2013
  9. Oct 08, 2013
  11. Oct 07, 2013
  13. Oct 03, 2013
    • Andre Przywara's avatar
      ARM: extend non-secure switch to also go into HYP mode · d4296887
      Andre Przywara authored 
      
For the KVM and XEN hypervisors to be usable, we need to enter the
kernel in HYP mode. Now that we already are in non-secure state,
HYP mode switching is within short reach.

While doing the non-secure switch, we have to enable the HVC
instruction and setup the HYP mode HVBAR (while still secure).

The actual switch is done by dropping back from a HYP mode handler
without actually leaving HYP mode, so we introduce a new handler
routine in our new secure exception vector table.

In the assembly switching routine we save and restore the banked LR
and SP registers around the hypercall to do the actual HYP mode
switch.

The C routine first checks whether we are in HYP mode already and
also whether the virtualization extensions are available. It also
checks whether the HYP mode switch was finally successful.
The bootm command part only calls the new function after the
non-secure switch.

Signed-off-by: default avatarAndre Przywara <andre.przywara@linaro.org>
      d4296887
    • Andre Przywara's avatar
      ARM: add SMP support for non-secure switch · ba6a1698
      Andre Przywara authored 
      
Currently the non-secure switch is only done for the boot processor.
To enable full SMP support, we have to switch all secondary cores
into non-secure state also.

So we add an entry point for secondary CPUs coming out of low-power
state and make sure we put them into WFI again after having switched
to non-secure state.
For this we acknowledge and EOI the wake-up IPI, then go into WFI.
Once being kicked out of it later, we sanity check that the start
address has actually been changed (since another attempt to switch
to non-secure would block the core) and jump to the new address.

The actual CPU kick is done by sending an inter-processor interrupt
via the GIC to all CPU interfaces except the requesting processor.
The secondary cores will then setup their respective GIC CPU
interface.
While this approach is pretty universal across several ARMv7 boards,
we make this function weak in case someone needs to tweak this for
a specific board.

The way of setting the secondary's start address is board specific,
but mostly different only in the actual SMP pen address, so we also
provide a weak default implementation and just depend on the proper
address to be set in the config file.

Signed-off-by: default avatarAndre Przywara <andre.przywara@linaro.org>
      ba6a1698
    • Andre Przywara's avatar
      ARM: trigger non-secure state switch during bootm execution · bb975455
      Andre Przywara authored 
      
To actually trigger the non-secure switch we just implemented, call
the switching routine from within the bootm command implementation.
This way we automatically enable this feature without further user
intervention.

Signed-off-by: default avatarAndre Przywara <andre.przywara@linaro.org>
      bb975455
    • Andre Przywara's avatar
      ARM: add C function to switch to non-secure state · 1ef92385
      Andre Przywara authored 
      
The core specific part of the work is done in the assembly routine
in nonsec_virt.S, introduced with the previous patch, but for the full
glory we need to setup the GIC distributor interface once for the
whole system, which is done in C here.
The routine is placed in arch/arm/cpu/armv7 to allow easy access from
other ARMv7 boards.

We check the availability of the security extensions first.

Since we need a safe way to access the GIC, we use the PERIPHBASE
registers on Cortex-A15 and A7 CPUs and do some sanity checks.
Boards not implementing the CBAR can override this value via a
configuration file variable.

Then we actually do the GIC enablement:
a) enable the GIC distributor, both for non-secure and secure state
   (GICD_CTLR[1:0] = 11b)
b) allow all interrupts to be handled from non-secure state
   (GICD_IGROUPRn = 0xFFFFFFFF)

The core specific GIC setup is then done in the assembly routine.

Signed-off-by: default avatarAndre Przywara <andre.przywara@linaro.org>
      1ef92385
    • Andre Przywara's avatar
      ARM: add assembly routine to switch to non-secure state · 16212b59
      Andre Przywara authored 
      
While actually switching to non-secure state is one thing, another
part of this process is to make sure that we still have full access
to the interrupt controller (GIC).
The GIC is fully aware of secure vs. non-secure state, some
registers are banked, others may be configured to be accessible from
secure state only.
To be as generic as possible, we get the GIC memory mapped address
based on the PERIPHBASE value in the CBAR register. Since this
register is not architecturally defined, we check the MIDR before to
be from an A15 or A7.
For CPUs not having the CBAR or boards with wrong information herein
we allow providing the base address as a configuration variable.

Now that we know the GIC address, we:
a) allow private interrupts to be delivered to the core
   (GICD_IGROUPR0 = 0xFFFFFFFF)
b) enable the CPU interface (GICC_CTLR[0] = 1)
c) set the priority filter to allow non-secure interrupts
   (GICC_PMR = 0xFF)

Also we allow access to all coprocessor interfaces from non-secure
state by writing the appropriate bits in the NSACR register.

The generic timer base frequency register is only accessible from
secure state, so we have to program it now. Actually this should be
done from primary firmware before, but some boards seems to omit
this, so if needed we do this here with a board specific value.
The Versatile Express board does not need this, so we remove the
frequency from the configuration file here.

After having switched to non-secure state, we also enable the
non-secure GIC CPU interface, since this register is banked.

Since we need to call this routine also directly from the smp_pen
later (where we don't have any stack), we can only use caller saved
registers r0-r3 and r12 to not mess with the compiler.

Signed-off-by: default avatarAndre Przywara <andre.przywara@linaro.org>
      16212b59
    • Andre Przywara's avatar
      ARM: add secure monitor handler to switch to non-secure state · 45b940d6
      Andre Przywara authored 
      
A prerequisite for using virtualization is to be in HYP mode, which
requires the CPU to be in non-secure state first.
Add a new file in arch/arm/cpu/armv7 to hold a monitor handler routine
which switches the CPU to non-secure state by setting the NS and
associated bits.
According to the ARM architecture reference manual this should not be
done in SVC mode, so we have to setup a SMC handler for this.
We create a new vector table to avoid interference with other boards.
The MVBAR register will be programmed later just before the smc call.

Signed-off-by: default avatarAndre Przywara <andre.przywara@linaro.org>
      45b940d6
    • Andre Przywara's avatar
      ARM: prepare armv7.h to be included from assembly source · d75ba503
      Andre Przywara authored 
      
armv7.h contains some useful constants, but also C prototypes.
To include it also in assembly files, protect the non-assembly
part appropriately.

Signed-off-by: default avatarAndre Przywara <andre.przywara@linaro.org>
      d75ba503
  15. Sep 27, 2013