On Mar 9, 2012, at 10:44 PM, Rusty Russell <rusty at rustcorp.com.au> wrote:
>
> From: Rusty Russell <rusty at rustcorp.com.au>
>
> If we do this the C-correct way, we use fewer casts and it's a bit clearer.
>
> Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
> ---
> arch/arm/include/asm/kvm_host.h | 6 +++-
> arch/arm/kvm/emulate.c | 60 ++++++++++++++++++++-------------------
> 2 files changed, 36 insertions(+), 30 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 8002903..e211d8e 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -86,7 +86,11 @@ enum cp15_regs {
> };
>
> struct kvm_vcpu_arch {
> - struct kvm_vcpu_regs regs;
> + /* We sometimes access these as an array for simplicity. */
> + union {
> + struct kvm_vcpu_regs regs;
> + u32 reg_array[sizeof(struct kvm_vcpu_regs) / sizeof(u32)];
> + };
>
> /* System control coprocessor (cp15) */
> u32 cp15[nr_cp15_regs];
> diff --git a/arch/arm/kvm/emulate.c b/arch/arm/kvm/emulate.c
> index 4f5f2de..108db38 100644
> --- a/arch/arm/kvm/emulate.c
> +++ b/arch/arm/kvm/emulate.c
> @@ -22,8 +22,10 @@
>
> #include "trace.h"
>
> -#define USR_REG_OFFSET(_reg) \
> - offsetof(struct kvm_vcpu_arch, regs.usr_regs[_reg])
> +#define REG_OFFSET(_reg) \
> + (offsetof(struct kvm_vcpu_regs, _reg) / sizeof(u32))
> +
> +#define USR_REG_OFFSET(_num) REG_OFFSET(usr_regs[_num])
>
> static const unsigned long vcpu_reg_offsets[MODE_SYS + 1][16] = {
> /* FIQ Registers */
> @@ -31,14 +33,14 @@ static const unsigned long vcpu_reg_offsets[MODE_SYS + 1][16] = {
> USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
> USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
> USR_REG_OFFSET(6), USR_REG_OFFSET(7),
> - offsetof(struct kvm_vcpu_arch, regs.fiq_regs[1]), /* r8 */
> - offsetof(struct kvm_vcpu_arch, regs.fiq_regs[1]), /* r9 */
> - offsetof(struct kvm_vcpu_arch, regs.fiq_regs[2]), /* r10 */
> - offsetof(struct kvm_vcpu_arch, regs.fiq_regs[3]), /* r11 */
> - offsetof(struct kvm_vcpu_arch, regs.fiq_regs[4]), /* r12 */
> - offsetof(struct kvm_vcpu_arch, regs.fiq_regs[5]), /* r13 */
> - offsetof(struct kvm_vcpu_arch, regs.fiq_regs[6]), /* r14 */
> - offsetof(struct kvm_vcpu_arch, regs.pc) /* r15 */
> + REG_OFFSET(fiq_regs[1]), /* r8 */
> + REG_OFFSET(fiq_regs[1]), /* r9 */
> + REG_OFFSET(fiq_regs[2]), /* r10 */
> + REG_OFFSET(fiq_regs[3]), /* r11 */
> + REG_OFFSET(fiq_regs[4]), /* r12 */
> + REG_OFFSET(fiq_regs[5]), /* r13 */
> + REG_OFFSET(fiq_regs[6]), /* r14 */
> + REG_OFFSET(pc) /* r15 */
> },
>
> /* IRQ Registers */
> @@ -48,9 +50,9 @@ static const unsigned long vcpu_reg_offsets[MODE_SYS + 1][16] = {
> USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
> USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
> USR_REG_OFFSET(12),
> - offsetof(struct kvm_vcpu_arch, regs.irq_regs[0]), /* r13 */
> - offsetof(struct kvm_vcpu_arch, regs.irq_regs[1]), /* r14 */
> - offsetof(struct kvm_vcpu_arch, regs.pc) /* r15 */
> + REG_OFFSET(irq_regs[0]), /* r13 */
> + REG_OFFSET(irq_regs[1]), /* r14 */
> + REG_OFFSET(pc) /* r15 */
> },
>
> /* SVC Registers */
> @@ -60,9 +62,9 @@ static const unsigned long vcpu_reg_offsets[MODE_SYS + 1][16] = {
> USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
> USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
> USR_REG_OFFSET(12),
> - offsetof(struct kvm_vcpu_arch, regs.svc_regs[0]), /* r13 */
> - offsetof(struct kvm_vcpu_arch, regs.svc_regs[1]), /* r14 */
> - offsetof(struct kvm_vcpu_arch, regs.pc) /* r15 */
> + REG_OFFSET(svc_regs[0]), /* r13 */
> + REG_OFFSET(svc_regs[1]), /* r14 */
> + REG_OFFSET(pc) /* r15 */
> },
>
> /* ABT Registers */
> @@ -72,9 +74,9 @@ static const unsigned long vcpu_reg_offsets[MODE_SYS + 1][16] = {
> USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
> USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
> USR_REG_OFFSET(12),
> - offsetof(struct kvm_vcpu_arch, regs.abt_regs[0]), /* r13 */
> - offsetof(struct kvm_vcpu_arch, regs.abt_regs[1]), /* r14 */
> - offsetof(struct kvm_vcpu_arch, regs.pc) /* r15 */
> + REG_OFFSET(abt_regs[0]), /* r13 */
> + REG_OFFSET(abt_regs[1]), /* r14 */
> + REG_OFFSET(pc) /* r15 */
> },
>
> /* UND Registers */
> @@ -84,9 +86,9 @@ static const unsigned long vcpu_reg_offsets[MODE_SYS + 1][16] = {
> USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
> USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
> USR_REG_OFFSET(12),
> - offsetof(struct kvm_vcpu_arch, regs.und_regs[0]), /* r13 */
> - offsetof(struct kvm_vcpu_arch, regs.und_regs[1]), /* r14 */
> - offsetof(struct kvm_vcpu_arch, regs.pc) /* r15 */
> + REG_OFFSET(und_regs[0]), /* r13 */
> + REG_OFFSET(und_regs[1]), /* r14 */
> + REG_OFFSET(pc) /* r15 */
> },
>
> /* USR Registers */
> @@ -96,9 +98,9 @@ static const unsigned long vcpu_reg_offsets[MODE_SYS + 1][16] = {
> USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
> USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
> USR_REG_OFFSET(12),
> - offsetof(struct kvm_vcpu_arch, regs.usr_regs[13]), /* r13 */
> - offsetof(struct kvm_vcpu_arch, regs.usr_regs[14]), /* r14 */
> - offsetof(struct kvm_vcpu_arch, regs.pc) /* r15 */
> + REG_OFFSET(usr_regs[13]), /* r13 */
> + REG_OFFSET(usr_regs[14]), /* r14 */
> + REG_OFFSET(pc) /* r15 */
> },
>
> /* SYS Registers */
> @@ -108,9 +110,9 @@ static const unsigned long vcpu_reg_offsets[MODE_SYS + 1][16] = {
> USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
> USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
> USR_REG_OFFSET(12),
> - offsetof(struct kvm_vcpu_arch, regs.usr_regs[13]), /* r13 */
> - offsetof(struct kvm_vcpu_arch, regs.usr_regs[14]), /* r14 */
> - offsetof(struct kvm_vcpu_arch, regs.pc) /* r15 */
> + REG_OFFSET(usr_regs[13]), /* r13 */
> + REG_OFFSET(usr_regs[14]), /* r14 */
> + REG_OFFSET(pc) /* r15 */
> },
> };
>
> @@ -123,7 +125,7 @@ u32 *kvm_vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num, u32 mode)
> BUG_ON(reg_num > 15);
> BUG_ON(mode > MODE_SYS);
>
> - return (u32 *)((void *)&vcpu->arch + vcpu_reg_offsets[mode][reg_num]);
> + return &vcpu->arch.reg_array[vcpu_reg_offsets[mode][reg_num]];
> }
>
> /******************************************************************************
I'm fine with this. Thanks.
