On Mon, Aug 20, 2018 at 04:06:59PM +1000, Paul Mackerras wrote:
> This fixes a bug which causes guest virtual addresses to get translated
> to guest real addresses incorrectly when the guest is using the HPT MMU
> and has more than 256GB of RAM, or more specifically has a HPT larger
> than 2GB. This has showed up in testing as a failure of the host to
> emulate doorbell instructions correctly on POWER9 for HPT guests with
> more than 256GB of RAM.
>
> The bug is that the HPTE index in kvmppc_mmu_book3s_64_hv_xlate()
> is stored as an int, and in forming the HPTE address, the index gets
> shifted left 4 bits as an int before being signed-extended to 64 bits.
> The simple fix is to make the variable a long int, matching the
> return type of kvmppc_hv_find_lock_hpte(), which is what calculates
> the index.
>
> Fixes: 697d3899dcb4 ("KVM: PPC: Implement MMIO emulation support for Book3S HV guests")
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>
Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
Unfortunately I haven't been able to get a hold of POWER9 time to test
it yet, still working on it.
> ---
> arch/powerpc/kvm/book3s_64_mmu_hv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> index 7f3a8cf..4c08f42 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> @@ -359,7 +359,7 @@ static int kvmppc_mmu_book3s_64_hv_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
> unsigned long pp, key;
> unsigned long v, orig_v, gr;
> __be64 *hptep;
> - int index;
> + long int index;
> int virtmode = vcpu->arch.shregs.msr & (data ? MSR_DR : MSR_IR);
>
> if (kvm_is_radix(vcpu->kvm))
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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