On Mon, Feb 15, 2016 at 12:55:08PM +1100, Alexey Kardashevskiy wrote:
> Upcoming multi-tce support (H_PUT_TCE_INDIRECT/H_STUFF_TCE hypercalls)
> will validate TCE (not to have unexpected bits) and IO address
> (to be within the DMA window boundaries).
>
> This introduces helpers to validate TCE and IO address. The helpers are
> exported as they compile into vmlinux (to work in realmode) and will be
> used later by KVM kernel module in virtual mode.
>
> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
> ---
> Changes:
> v3:
> * inverted @mask in kvmppc_tce_validate() to match the same variable in
> kvmppc_ioba_validate()
> * s/arithmetial/arithmetic/
> * s/should be enabled/would have to be enabled/
>
> v2:
> * added note to the commit log about why new helpers are exported
> * did not add a note that xxx_validate() validate TCEs for KVM (not for
> host kernel DMA) as the helper names and file location tell what are
> they for
> ---
> arch/powerpc/include/asm/kvm_ppc.h | 4 ++
> arch/powerpc/kvm/book3s_64_vio_hv.c | 89 ++++++++++++++++++++++++++++++++-----
> 2 files changed, 83 insertions(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
> index 2241d53..9513911 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -166,6 +166,10 @@ extern int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu);
>
> extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
> struct kvm_create_spapr_tce *args);
> +extern long kvmppc_ioba_validate(struct kvmppc_spapr_tce_table *stt,
> + unsigned long ioba, unsigned long npages);
> +extern long kvmppc_tce_validate(struct kvmppc_spapr_tce_table *tt,
> + unsigned long tce);
> extern long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
> unsigned long ioba, unsigned long tce);
> extern long kvmppc_h_get_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
> diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c
> index 0ce4ffb..b608fdd 100644
> --- a/arch/powerpc/kvm/book3s_64_vio_hv.c
> +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
> @@ -36,6 +36,7 @@
> #include <asm/kvm_host.h>
> #include <asm/udbg.h>
> #include <asm/iommu.h>
> +#include <asm/tce.h>
>
> #define TCES_PER_PAGE (PAGE_SIZE / sizeof(u64))
>
> @@ -64,7 +65,7 @@ static struct kvmppc_spapr_tce_table *kvmppc_find_table(struct kvm_vcpu *vcpu,
> * WARNING: This will be called in real-mode on HV KVM and virtual
> * mode on PR KVM
> */
> -static long kvmppc_ioba_validate(struct kvmppc_spapr_tce_table *stt,
> +long kvmppc_ioba_validate(struct kvmppc_spapr_tce_table *stt,
> unsigned long ioba, unsigned long npages)
> {
> unsigned long mask = (1ULL << IOMMU_PAGE_SHIFT_4K) - 1;
> @@ -76,6 +77,79 @@ static long kvmppc_ioba_validate(struct kvmppc_spapr_tce_table *stt,
>
> return H_SUCCESS;
> }
> +EXPORT_SYMBOL_GPL(kvmppc_ioba_validate);
> +
> +/*
> + * Validates TCE address.
> + * At the moment flags and page mask are validated.
> + * As the host kernel does not access those addresses (just puts them
> + * to the table and user space is supposed to process them), we can skip
> + * checking other things (such as TCE is a guest RAM address or the page
> + * was actually allocated).
> + *
> + * WARNING: This will be called in real-mode on HV KVM and virtual
> + * mode on PR KVM
> + */
> +long kvmppc_tce_validate(struct kvmppc_spapr_tce_table *stt, unsigned long tce)
> +{
> + unsigned long mask =
> + ~(IOMMU_PAGE_MASK_4K | TCE_PCI_WRITE | TCE_PCI_READ);
> +
> + if (tce & mask)
> + return H_PARAMETER;
> +
> + return H_SUCCESS;
> +}
> +EXPORT_SYMBOL_GPL(kvmppc_tce_validate);
> +
> +/* Note on the use of page_address() in real mode,
> + *
> + * It is safe to use page_address() in real mode on ppc64 because
> + * page_address() is always defined as lowmem_page_address()
> + * which returns __va(PFN_PHYS(page_to_pfn(page))) which is arithmetic
> + * operation and does not access page struct.
> + *
> + * Theoretically page_address() could be defined different
> + * but either WANT_PAGE_VIRTUAL or HASHED_PAGE_VIRTUAL
> + * would have to be enabled.
> + * WANT_PAGE_VIRTUAL is never enabled on ppc32/ppc64,
> + * HASHED_PAGE_VIRTUAL could be enabled for ppc32 only and only
> + * if CONFIG_HIGHMEM is defined. As CONFIG_SPARSEMEM_VMEMMAP
> + * is not expected to be enabled on ppc32, page_address()
> + * is safe for ppc32 as well.
> + *
> + * WARNING: This will be called in real-mode on HV KVM and virtual
> + * mode on PR KVM
> + */
> +static u64 *kvmppc_page_address(struct page *page)
> +{
> +#if defined(HASHED_PAGE_VIRTUAL) || defined(WANT_PAGE_VIRTUAL)
> +#error TODO: fix to avoid page_address() here
> +#endif
> + return (u64 *) page_address(page);
> +}
> +
> +/*
> + * Handles TCE requests for emulated devices.
> + * Puts guest TCE values to the table and expects user space to convert them.
> + * Called in both real and virtual modes.
> + * Cannot fail so kvmppc_tce_validate must be called before it.
> + *
> + * WARNING: This will be called in real-mode on HV KVM and virtual
> + * mode on PR KVM
> + */
> +void kvmppc_tce_put(struct kvmppc_spapr_tce_table *stt,
> + unsigned long idx, unsigned long tce)
> +{
> + struct page *page;
> + u64 *tbl;
> +
> + page = stt->pages[idx / TCES_PER_PAGE];
> + tbl = kvmppc_page_address(page);
> +
> + tbl[idx % TCES_PER_PAGE] = tce;
> +}
> +EXPORT_SYMBOL_GPL(kvmppc_tce_put);
>
> /* WARNING: This will be called in real-mode on HV KVM and virtual
> * mode on PR KVM
> @@ -85,9 +159,6 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
> {
> struct kvmppc_spapr_tce_table *stt = kvmppc_find_table(vcpu, liobn);
> long ret;
> - unsigned long idx;
> - struct page *page;
> - u64 *tbl;
>
> /* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
> /* liobn, ioba, tce); */
> @@ -99,13 +170,11 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
> if (ret != H_SUCCESS)
> return ret;
>
> - idx = ioba >> IOMMU_PAGE_SHIFT_4K;
> - page = stt->pages[idx / TCES_PER_PAGE];
> - tbl = (u64 *)page_address(page);
> + ret = kvmppc_tce_validate(stt, tce);
> + if (ret != H_SUCCESS)
> + return ret;
>
> - /* FIXME: Need to validate the TCE itself */
> - /* udbg_printf("tce @ %p\n", &tbl[idx % TCES_PER_PAGE]); */
> - tbl[idx % TCES_PER_PAGE] = tce;
> + kvmppc_tce_put(stt, ioba >> IOMMU_PAGE_SHIFT_4K, tce);
>
> return H_SUCCESS;
> }
--
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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