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target-ppc: ppc64 target's virtio can be either endian. (v3)

Message ID 20140117135211.27377.91848.stgit@bahia.local
State New
Headers show

Commit Message

Greg Kurz Jan. 17, 2014, 1:52 p.m. UTC 
We base it on the OS endian, as reflected by the endianness of the
interrupt vectors (handled through the ILE bit in the LPCR register).

This patch implements virtio_get_byteswap() over LPCR.

Using first_cpu to fetch the registers from KVM may look arbitrary
and awkward, but it is okay because KVM sets/unsets the ILE bit on
all CPUs.

Changes in v3:
-  dropped the explicit calls to kvm_[get|put]_one_reg as LPCR is
   now properly handled by the generic SPR code.
Changes in v2:
- call cpu_synchronize_state() instead of kvm_arch_get_registers().

Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
---
 target-ppc/misc_helper.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

Comments

Alexander Graf Jan. 20, 2014, 2:36 p.m. UTC | #1 
On 17.01.2014, at 14:52, Greg Kurz <gkurz@linux.vnet.ibm.com> wrote:

> We base it on the OS endian, as reflected by the endianness of the
> interrupt vectors (handled through the ILE bit in the LPCR register).
> 
> This patch implements virtio_get_byteswap() over LPCR.
> 
> Using first_cpu to fetch the registers from KVM may look arbitrary
> and awkward, but it is okay because KVM sets/unsets the ILE bit on
> all CPUs.
> 
> Changes in v3:
> -  dropped the explicit calls to kvm_[get|put]_one_reg as LPCR is
>   now properly handled by the generic SPR code.
> Changes in v2:
> - call cpu_synchronize_state() instead of kvm_arch_get_registers().
> 
> Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> Reviewed-by: Alexander Graf <agraf@suse.de>
> ---
> target-ppc/misc_helper.c |   12 ++++++++++++
> 1 file changed, 12 insertions(+)
> 
> diff --git a/target-ppc/misc_helper.c b/target-ppc/misc_helper.c
> index 616aab6..e8fc8a3 100644
> --- a/target-ppc/misc_helper.c
> +++ b/target-ppc/misc_helper.c
> @@ -20,6 +20,8 @@
> #include "helper.h"
> 
> #include "helper_regs.h"
> +#include "hw/virtio/virtio.h"
> +#include "sysemu/kvm.h"
> 
> /*****************************************************************************/
> /* SPR accesses */
> @@ -116,3 +118,13 @@ void ppc_store_msr(CPUPPCState *env, target_ulong value)
> {
>     hreg_store_msr(env, value, 0);
> }
> +
> +bool virtio_get_byteswap(void)
> +{
> +    PowerPCCPU *cp = POWERPC_CPU(first_cpu);
> +    CPUPPCState *env = &cp->env;
> +
> +    cpu_synchronize_state(first_cpu);

LPCR_ILE only gets modified by QEMU, so you can even get rid of the synchronize call :).

Either way, this can only go in after the generic virtio byteswap mechanics are merged.


Alex

> +
> +    return env->spr[SPR_LPCR] & LPCR_ILE;
> +}
>
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Patch

diff --git a/target-ppc/misc_helper.c b/target-ppc/misc_helper.c
index 616aab6..e8fc8a3 100644
--- a/target-ppc/misc_helper.c
+++ b/target-ppc/misc_helper.c
@@ -20,6 +20,8 @@ 
 #include "helper.h"
 
 #include "helper_regs.h"
+#include "hw/virtio/virtio.h"
+#include "sysemu/kvm.h"
 
 /*****************************************************************************/
 /* SPR accesses */
@@ -116,3 +118,13 @@  void ppc_store_msr(CPUPPCState *env, target_ulong value)
 {
     hreg_store_msr(env, value, 0);
 }
+
+bool virtio_get_byteswap(void)
+{
+    PowerPCCPU *cp = POWERPC_CPU(first_cpu);
+    CPUPPCState *env = &cp->env;
+
+    cpu_synchronize_state(first_cpu);
+
+    return env->spr[SPR_LPCR] & LPCR_ILE;
+}