Re: [Qemu-devel] [PATCH] arm/virt: Use PSCI v0.2 function IDs in the DT when KVM uses PSCI v0.2

[Peter Maydell]

On 7 August 2014 17:30, Christoffer Dall <address@hidden> wrote:
> The current code supplies the PSCI v0.1 funciton IDs in the DT even when

"function"

> KVM uses PSCI v0.2.
>
> This will break guest kernels that only support PSCI v0.1 as they will
> use the IDs provided in the DT.  Guest kernels with PSCI v0.2 support
> are not affected by this patch, because they ignore the function IDs in
> the device tree and rely on the architecture definition.
>
> Define QEMU versions of the constants and check that they correspond to
> the Linux defines on Linux build hosts.  After this patch, both guest
> kernels with PSCI v0.1 support and guest kernels with PSCI v0.2 should
> work.
>
> Tested on TC2 for 32-bit and APM Mustang for 64-bit (aarch64 guest
> only).  Both cases tested with 3.14 and linus/master and verified I
> could bring up 2 cpus with both guest kernels.
>
> Signed-off-by: Christoffer Dall <address@hidden>
> ---
>  hw/arm/virt.c           | 25 ++++++++++++++++++++++---
>  target-arm/kvm-consts.h | 23 +++++++++++++++++++++++
>  2 files changed, 45 insertions(+), 3 deletions(-)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index ba94298..4e882bc 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -194,20 +194,39 @@ static void fdt_add_psci_node(const VirtBoardInfo *vbi)
>
>      /* No PSCI for TCG yet */
>      if (kvm_enabled()) {
> +        uint32_t cpu_off_fn;
> +        uint32_t cpu_on_fn;
> +        uint32_t migrate_fn;
> +
>          qemu_fdt_add_subnode(fdt, "/psci");
>          if (armcpu->psci_version == 2) {
>              const char comp[] = "arm,psci-0.2\0arm,psci";
>              qemu_fdt_setprop(fdt, "/psci", "compatible", comp, sizeof(comp));
> +
> +            if (arm_feature(&armcpu->env, ARM_FEATURE_AARCH64)) {
> +                cpu_off_fn = QEMU_PSCI_0_2_FN_CPU_OFF;
> +                cpu_on_fn = QEMU_PSCI_0_2_FN64_CPU_ON;
> +                migrate_fn = QEMU_PSCI_0_2_FN64_MIGRATE;
> +            } else {
> +                cpu_off_fn = QEMU_PSCI_0_2_FN_CPU_OFF;
> +                cpu_on_fn = QEMU_PSCI_0_2_FN_CPU_ON;
> +                migrate_fn = QEMU_PSCI_0_2_FN_MIGRATE;
> +            }
>          } else {
>              qemu_fdt_setprop_string(fdt, "/psci", "compatible", "arm,psci");
> +
> +            cpu_off_fn = PSCI_FN_CPU_OFF;
> +            cpu_on_fn = PSCI_FN_CPU_ON;
> +            migrate_fn = PSCI_FN_MIGRATE;


I see that linux/psci.h defines PSCI_0_2_FN64_CPU_SUSPEND
and PSCI_0_2_FN_CPU_SUSPEND, neither of which are
the same as PSCI_FN_CPU_SUSPEND. Shouldn't we be
using the 0.2 values for SUSPEND too?

(Sharing the CPU_OFF value is correct by the spec I see,
but it would probably be better outside the if() and with a comment,
since it otherwise looks a lot like an error.)

>          }
>
>          qemu_fdt_setprop_string(fdt, "/psci", "method", "hvc");
>          qemu_fdt_setprop_cell(fdt, "/psci", "cpu_suspend",
>                                    PSCI_FN_CPU_SUSPEND);
> -        qemu_fdt_setprop_cell(fdt, "/psci", "cpu_off", PSCI_FN_CPU_OFF);
> -        qemu_fdt_setprop_cell(fdt, "/psci", "cpu_on", PSCI_FN_CPU_ON);
> -        qemu_fdt_setprop_cell(fdt, "/psci", "migrate", PSCI_FN_MIGRATE);
> +
> +        qemu_fdt_setprop_cell(fdt, "/psci", "cpu_off", cpu_off_fn);
> +        qemu_fdt_setprop_cell(fdt, "/psci", "cpu_on", cpu_on_fn);
> +        qemu_fdt_setprop_cell(fdt, "/psci", "migrate", migrate_fn);
>      }
>  }
>
> diff --git a/target-arm/kvm-consts.h b/target-arm/kvm-consts.h
> index 6009a33..a8df135 100644
> --- a/target-arm/kvm-consts.h
> +++ b/target-arm/kvm-consts.h
> @@ -17,6 +17,7 @@
>  #ifdef CONFIG_KVM
>  #include "qemu/compiler.h"
>  #include <linux/kvm.h>
> +#include <linux/psci.h>
>
>  #define MISMATCH_CHECK(X, Y) QEMU_BUILD_BUG_ON(X != Y)
>
> @@ -50,6 +51,28 @@ MISMATCH_CHECK(PSCI_FN_CPU_OFF, KVM_PSCI_FN_CPU_OFF)
>  MISMATCH_CHECK(PSCI_FN_CPU_ON, KVM_PSCI_FN_CPU_ON)
>  MISMATCH_CHECK(PSCI_FN_MIGRATE, KVM_PSCI_FN_MIGRATE)
>
> +#define QEMU_PSCI_0_2_FN_BASE 0x84000000
> +#define QEMU_PSCI_0_2_FN(n) (QEMU_PSCI_0_2_FN_BASE + (n))
> +
> +#define QEMU_PSCI_0_2_64BIT 0x40000000
> +#define QEMU_PSCI_0_2_FN64_BASE \
> +        (QEMU_PSCI_0_2_FN_BASE + QEMU_PSCI_0_2_64BIT)
> +#define QEMU_PSCI_0_2_FN64(n) (QEMU_PSCI_0_2_FN64_BASE + (n))
> +
> +#define QEMU_PSCI_0_2_FN_CPU_OFF QEMU_PSCI_0_2_FN(2)
> +#define QEMU_PSCI_0_2_FN_CPU_ON QEMU_PSCI_0_2_FN(3)
> +#define QEMU_PSCI_0_2_FN_MIGRATE QEMU_PSCI_0_2_FN(5)
> +
> +#define QEMU_PSCI_0_2_FN64_CPU_OFF QEMU_PSCI_0_2_FN64(2)
> +#define QEMU_PSCI_0_2_FN64_CPU_ON QEMU_PSCI_0_2_FN64(3)
> +#define QEMU_PSCI_0_2_FN64_MIGRATE QEMU_PSCI_0_2_FN64(5)
> +
> +MISMATCH_CHECK(QEMU_PSCI_0_2_FN_CPU_OFF, PSCI_0_2_FN_CPU_OFF)
> +MISMATCH_CHECK(QEMU_PSCI_0_2_FN_CPU_ON, PSCI_0_2_FN_CPU_ON)
> +MISMATCH_CHECK(QEMU_PSCI_0_2_FN_MIGRATE, PSCI_0_2_FN_MIGRATE)
> +MISMATCH_CHECK(QEMU_PSCI_0_2_FN64_CPU_ON, PSCI_0_2_FN64_CPU_ON)
> +MISMATCH_CHECK(QEMU_PSCI_0_2_FN64_MIGRATE, PSCI_0_2_FN64_MIGRATE)
> +

This now clashes awkwardly with the way we previously had
PSCI_* for the QEMU versions and KVM_PSCI_* for the
kernel header versions, because the kernel's moved over
to PSCI_*. We should probably (in a separate patch) rename
the PSCI_FN* constants in kvm-consts.h to QEMU_PSCI_0_1_*.

thanks
-- PMM