On Fri, Mar 24, 2017 at 05:49:22PM +1100, Alexey Kardashevskiy wrote:
> PR KVM page fault handler performs eaddr to pte translation for a guest,
> however kvmppc_mmu_book3s_64_xlate() does not preserve WIMG bits
> (storage control) in the kvmppc_pte struct. If PR KVM is running as
> a second level guest under HV KVM, and PR KVM tries inserting HPT entry,
> this fails in HV KVM if it already has this mapping.
>
> This preserves WIMG bits between kvmppc_mmu_book3s_64_xlate() and
> kvmppc_mmu_map_page().
>
> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
> ---
>
> This allows MMIO BAR mapping for nested guest with VFIO.
>
> This is the check in HV KVM which failed:
>
> arch/powerpc/kvm/book3s_hv_rm_mmu.c
> long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
> [...]
>
> /*If we had host pte mapping then Check WIMG */
> if (ptep && !hpte_cache_flags_ok(ptel, is_ci)) {
> if (is_ci)
> return H_PARAMETER;
> /*
> * Allow guest to map emulated device memory as
> * uncacheable, but actually make it cacheable.
> */
> ptel &= ~(HPTE_R_W|HPTE_R_I|HPTE_R_G);
> ptel |= HPTE_R_M;
> }
> ---
> arch/powerpc/include/asm/kvm_host.h | 1 +
> arch/powerpc/kvm/book3s_64_mmu.c | 1 +
> arch/powerpc/kvm/book3s_64_mmu_host.c | 2 ++
> arch/powerpc/kvm/book3s_pr.c | 2 +-
> 4 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index 7bba8f415627..bf6822cd4f86 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -345,6 +345,7 @@ struct kvmppc_pte {
> bool may_read : 1;
> bool may_write : 1;
> bool may_execute : 1;
> + unsigned long wimg;
> u8 page_size; /* MMU_PAGE_xxx */
> };
>
> diff --git a/arch/powerpc/kvm/book3s_64_mmu.c b/arch/powerpc/kvm/book3s_64_mmu.c
> index 70153578131a..29ebe2fd5867 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu.c
> @@ -319,6 +319,7 @@ static int kvmppc_mmu_book3s_64_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
> gpte->may_execute = true;
> gpte->may_read = false;
> gpte->may_write = false;
> + gpte->wimg = r & HPTE_R_WIMG;
>
> switch (pp) {
> case 0:
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c b/arch/powerpc/kvm/book3s_64_mmu_host.c
> index 4b4e927c4822..145a61892c48 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_host.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_host.c
> @@ -145,6 +145,8 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte,
> else
> kvmppc_mmu_flush_icache(pfn);
>
> + rflags = (rflags & ~HPTE_R_WIMG) | orig_pte->wimg;
> +
> /*
> * Use 64K pages if possible; otherwise, on 64K page kernels,
> * we need to transfer 4 more bits from guest real to host real addr.
> diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
> index ce437b98477e..f026b062c0ed 100644
> --- a/arch/powerpc/kvm/book3s_pr.c
> +++ b/arch/powerpc/kvm/book3s_pr.c
> @@ -537,7 +537,7 @@ int kvmppc_handle_pagefault(struct kvm_run *run, struct kvm_vcpu *vcpu,
> int r = RESUME_GUEST;
> int relocated;
> int page_found = 0;
> - struct kvmppc_pte pte;
> + struct kvmppc_pte pte = { 0 };
> bool dr = (kvmppc_get_msr(vcpu) & MSR_DR) ? true : false;
> bool ir = (kvmppc_get_msr(vcpu) & MSR_IR) ? true : false;
> u64 vsid;
--
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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