From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoffer Dall <christoffer.dall@linaro.org>
Subject: Re: [PATCH v4] arm64: fix VTTBR_BADDR_MASK
Date: Tue, 19 Aug 2014 14:22:36 +0200
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	Sungjinn Chung <sungjinn.chung@samsung.com>,
	Jungseok Lee <jays.lee@samsung.com>
To: Joel Schopp <joel.schopp@amd.com>
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On Mon, Aug 18, 2014 at 03:30:58PM -0500, Joel Schopp wrote:
> 
>  #endif /* __ARM_KVM_MMU_H__ */
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 16e7994..70f0f02 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -521,6 +521,7 @@ int create_hyp_io_mappings(void *from, void *to, phys_addr_t phys_addr)
>   */
>  int kvm_alloc_stage2_pgd(struct kvm *kvm)
>  {
> +	unsigned int s2_pgds, s2_pgd_order;
>  	pgd_t *pgd;
>  
>  	if (kvm->arch.pgd != NULL) {
> @@ -528,10 +529,18 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm)
>  		return -EINVAL;
>  	}
>  
> -	pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, S2_PGD_ORDER);
> +	s2_pgds = (1 << (kvm_get_phys_addr_shift() - PGDIR_SHIFT));
> +	s2_pgd_order = get_order(s2_pgds * sizeof(pgd_t));
> +
> +	pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, s2_pgd_order);
>  	if (!pgd)
>  		return -ENOMEM;
>  
> +	if ((unsigned long)pgd & ~vttbr_baddr_mask) {
> +		kvm_err("Stage-2 pgd not correctly aligned: %p\n", pgd);
> +		return -EFAULT;
> +	}
> 
> 
> There are two problems that I've found here.  The first problem is that
> vttbr_baddr_mask isn't allocated yet at this point in the code.

allocated? you mean assigned?
aren't you setting vttbr_baddr_mask in kvm_arch_init()?  that's
certainly called before kvm_arch_init_vm().


> The
> second problem is that pgd is a virtual address, ie pgd ==
> 0xfffffe03bbb40000 while the vttbr masks off the high bits for a
> physical address, ie vttbr_baddr_mask=0x00007ffffffe0000 .  Even
> correcting for those issues I haven't been able to make this check work
> properly.  I'll resend v5 the patch with all the other suggested changes.
> 

What are the issues that you face?  Iow. what is the alignment of the
returned physical address?

(You should be able to just to virt_to_phys(pgd) and use that to test
for the vttbr_baddr_mask).


Thanks,
-Christoffer