From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Sat, 21 Jun 2014 10:58:13 +0100 Subject: [PATCH v4 11/14] ARM64: KVM: fix vgic_bitmap_get_reg function for BE 64bit case In-Reply-To: <20140614150451.GG14023@lvm> (Christoffer Dall's message of "Sat, 14 Jun 2014 16:04:51 +0100") References: <1402590613-3341-1-git-send-email-victor.kamensky@linaro.org> <1402590613-3341-12-git-send-email-victor.kamensky@linaro.org> <20140614150451.GG14023@lvm> Message-ID: <86wqcak2iy.fsf@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sat, Jun 14 2014 at 04:04:51 PM, Christoffer Dall wrote: > On Thu, Jun 12, 2014 at 09:30:10AM -0700, Victor Kamensky wrote: >> Fix vgic_bitmap_get_reg function to return 'right' word address of >> 'unsigned long' bitmap value in case of BE 64bit image. >> >> Signed-off-by: Victor Kamensky >> --- >> virt/kvm/arm/vgic.c | 24 ++++++++++++++++++++++-- >> 1 file changed, 22 insertions(+), 2 deletions(-) >> >> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c >> index 529c336..b4ffd82 100644 >> --- a/virt/kvm/arm/vgic.c >> +++ b/virt/kvm/arm/vgic.c >> @@ -101,14 +101,34 @@ static u32 vgic_nr_lr; >> >> static unsigned int vgic_maint_irq; >> >> +/* >> + * struct vgic_bitmap contains unions that provide two views of >> + * the same data. In one case it is an array of registers of >> + * u32's, and in the other case it is a bitmap of unsigned >> + * longs. >> + * >> + * This does not work on 64-bit BE systems, because the bitmap access >> + * will store two consecutive 32-bit words with the higher-addressed >> + * register's bits at the lower index and the lower-addressed register's >> + * bits at the higher index. >> + * >> + * Therefore, swizzle the register index when accessing the 32-bit word >> + * registers to access the right register's value. >> + */ >> +#if defined(CONFIG_CPU_BIG_ENDIAN) && BITS_PER_LONG == 64 >> +#define REG_OFFSET_SWIZZLE 1 >> +#else >> +#define REG_OFFSET_SWIZZLE 0 >> +#endif >> + >> static u32 *vgic_bitmap_get_reg(struct vgic_bitmap *x, >> int cpuid, u32 offset) >> { >> offset >>= 2; >> if (!offset) >> - return x->percpu[cpuid].reg; >> + return x->percpu[cpuid].reg + (offset ^ REG_OFFSET_SWIZZLE); >> else >> - return x->shared.reg + offset - 1; >> + return x->shared.reg + ((offset - 1) ^ REG_OFFSET_SWIZZLE); >> } >> >> static int vgic_bitmap_get_irq_val(struct vgic_bitmap *x, >> -- >> 1.8.1.4 >> > > I had wished there was a cleaner way to abstract this, but I can't think > of a cleaner solution, and restructuring the whole thing would be very > invasive. > > I'm curious to hear from Marc on this one, but you can add: > > Reviewed-by: Christoffer Dall > > because it looks correct. > > Thanks for picking up my suggestion on the commenting. I tried hard to find another solution, but I think this is unfortunately the best we can have... ;-) So: Acked-by: Marc Zyngier I will have to fold in a similar solution for the vgic-dyn series. Thanks, M. -- Jazz is not dead. It just smells funny.