lkml.org 
[lkml]   [2021]   [Aug]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH v4 11/21] KVM: arm64: Allow populating software bits
    Hi Quentin,

    On Mon, Aug 9, 2021 at 5:25 PM Quentin Perret <qperret@google.com> wrote:
    >
    > Introduce infrastructure allowing to manipulate software bits in stage-1
    > and stage-2 page-tables using additional entries in the kvm_pgtable_prot
    > enum.
    >
    > This is heavily inspired by Marc's implementation of a similar feature
    > in the NV patch series, but adapted to allow stage-1 changes as well:
    >
    > https://lore.kernel.org/kvmarm/20210510165920.1913477-56-maz@kernel.org/
    >
    > Suggested-by: Marc Zyngier <maz@kernel.org>
    > Signed-off-by: Quentin Perret <qperret@google.com>
    > ---

    Reviewed-by: Fuad Tabba <tabba@google.com>

    Thanks,
    /fuad

    > arch/arm64/include/asm/kvm_pgtable.h | 12 +++++++++++-
    > arch/arm64/kvm/hyp/pgtable.c | 5 +++++
    > 2 files changed, 16 insertions(+), 1 deletion(-)
    >
    > diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
    > index 2c090b0eee77..ff9d52f8073a 100644
    > --- a/arch/arm64/include/asm/kvm_pgtable.h
    > +++ b/arch/arm64/include/asm/kvm_pgtable.h
    > @@ -121,6 +121,10 @@ enum kvm_pgtable_stage2_flags {
    > * @KVM_PGTABLE_PROT_W: Write permission.
    > * @KVM_PGTABLE_PROT_R: Read permission.
    > * @KVM_PGTABLE_PROT_DEVICE: Device attributes.
    > + * @KVM_PGTABLE_PROT_SW0: Software bit 0.
    > + * @KVM_PGTABLE_PROT_SW1: Software bit 1.
    > + * @KVM_PGTABLE_PROT_SW2: Software bit 2.
    > + * @KVM_PGTABLE_PROT_SW3: Software bit 3.
    > */
    > enum kvm_pgtable_prot {
    > KVM_PGTABLE_PROT_X = BIT(0),
    > @@ -128,6 +132,11 @@ enum kvm_pgtable_prot {
    > KVM_PGTABLE_PROT_R = BIT(2),
    >
    > KVM_PGTABLE_PROT_DEVICE = BIT(3),
    > +
    > + KVM_PGTABLE_PROT_SW0 = BIT(55),
    > + KVM_PGTABLE_PROT_SW1 = BIT(56),
    > + KVM_PGTABLE_PROT_SW2 = BIT(57),
    > + KVM_PGTABLE_PROT_SW3 = BIT(58),
    > };
    >
    > #define KVM_PGTABLE_PROT_RW (KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W)
    > @@ -420,7 +429,8 @@ kvm_pte_t kvm_pgtable_stage2_mkold(struct kvm_pgtable *pgt, u64 addr);
    > * If there is a valid, leaf page-table entry used to translate @addr, then
    > * relax the permissions in that entry according to the read, write and
    > * execute permissions specified by @prot. No permissions are removed, and
    > - * TLB invalidation is performed after updating the entry.
    > + * TLB invalidation is performed after updating the entry. Software bits cannot
    > + * be set or cleared using kvm_pgtable_stage2_relax_perms().
    > *
    > * Return: 0 on success, negative error code on failure.
    > */
    > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
    > index e25d829587b9..cff744136044 100644
    > --- a/arch/arm64/kvm/hyp/pgtable.c
    > +++ b/arch/arm64/kvm/hyp/pgtable.c
    > @@ -357,6 +357,7 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep)
    > attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S1_AP, ap);
    > attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S1_SH, sh);
    > attr |= KVM_PTE_LEAF_ATTR_LO_S1_AF;
    > + attr |= prot & KVM_PTE_LEAF_ATTR_HI_SW;
    > *ptep = attr;
    >
    > return 0;
    > @@ -558,6 +559,7 @@ static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot p
    >
    > attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh);
    > attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF;
    > + attr |= prot & KVM_PTE_LEAF_ATTR_HI_SW;
    > *ptep = attr;
    >
    > return 0;
    > @@ -1025,6 +1027,9 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr,
    > u32 level;
    > kvm_pte_t set = 0, clr = 0;
    >
    > + if (prot & KVM_PTE_LEAF_ATTR_HI_SW)
    > + return -EINVAL;
    > +
    > if (prot & KVM_PGTABLE_PROT_R)
    > set |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R;
    >
    > --
    > 2.32.0.605.g8dce9f2422-goog
    >

    \
     
     \ /
      Last update: 2021-08-10 06:57    [W:5.296 / U:0.060 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site