KVM: ARM: Demux CCSIDR in the userspace API

The Cache Size Selection Register (CSSELR) selects the current Cache
Size ID Register (CCSIDR).  You write which cache you are interested
in to CSSELR, and read the information out of CCSIDR.

Which cache numbers are valid is known by reading the Cache Level ID
Register (CLIDR).

To export this state to userspace, we add a KVM_REG_ARM_DEMUX
numberspace (17), which uses 8 bits to represent which register is
being demultiplexed (0 for CCSIDR), and the lower 8 bits to represent
this demultiplexing (in our case, the CSSELR value, which is 4 bits).

Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
index 53f45f146875..71ae27ec0599 100644
--- a/arch/arm/include/uapi/asm/kvm.h
+++ b/arch/arm/include/uapi/asm/kvm.h
@@ -104,6 +104,15 @@ struct kvm_arch_memory_slot {
 #define KVM_REG_ARM_CORE                (0x0010 << KVM_REG_ARM_COPROC_SHIFT)
 #define KVM_REG_ARM_CORE_REG(name)      (offsetof(struct kvm_regs, name) / 4)
 
+/* Some registers need more space to represent values. */
+#define KVM_REG_ARM_DEMUX               (0x0011 << KVM_REG_ARM_COPROC_SHIFT)
+#define KVM_REG_ARM_DEMUX_ID_MASK       0x000000000000FF00
+#define KVM_REG_ARM_DEMUX_ID_SHIFT      8
+#define KVM_REG_ARM_DEMUX_ID_CCSIDR     (0x00 << KVM_REG_ARM_DEMUX_ID_SHIFT)
+#define KVM_REG_ARM_DEMUX_VAL_MASK      0x00000000000000FF
+#define KVM_REG_ARM_DEMUX_VAL_SHIFT     0
+
+
 /* KVM_IRQ_LINE irq field index values */
 #define KVM_ARM_IRQ_TYPE_SHIFT          24
 #define KVM_ARM_IRQ_TYPE_MASK           0xff