On 19/03/2019 15:04, Suraj Jitindar Singh wrote:
> Implement a real mode handler for the H_CALL H_PAGE_INIT which can be
> used to zero or copy a guest page. The page is defined to be 4k and must
> be 4k aligned.
>
> The in-kernel real mode handler halves the time to handle this H_CALL
> compared to handling it in userspace for a hash guest.
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
> ---
> arch/powerpc/include/asm/kvm_ppc.h | 2 +
> arch/powerpc/kvm/book3s_hv_rm_mmu.c | 144 ++++++++++++++++++++++++++++++++
> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 2 +-
> 3 files changed, 147 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
> index 8e8bb1299a0e..f34f290463aa 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -653,6 +653,8 @@ long kvmppc_h_clear_ref(struct kvm_vcpu *vcpu, unsigned long flags,
> unsigned long pte_index);
> long kvmppc_h_clear_mod(struct kvm_vcpu *vcpu, unsigned long flags,
> unsigned long pte_index);
> +long kvmppc_rm_h_page_init(struct kvm_vcpu *vcpu, unsigned long flags,
> + unsigned long dest, unsigned long src);
> long kvmppc_hpte_hv_fault(struct kvm_vcpu *vcpu, unsigned long addr,
> unsigned long slb_v, unsigned int status, bool data);
> unsigned long kvmppc_rm_h_xirr(struct kvm_vcpu *vcpu);
> diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> index 3b3791ed74a6..26cfe1480ff5 100644
> --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> @@ -867,6 +867,150 @@ long kvmppc_h_clear_mod(struct kvm_vcpu *vcpu, unsigned long flags,
> return ret;
> }
>
> +static int kvmppc_get_hpa(struct kvm_vcpu *vcpu, unsigned long gpa,
> + int writing, unsigned long *hpa,
> + struct kvm_memory_slot **memslot_p)
> +{
> + struct kvm *kvm = vcpu->kvm;
> + struct kvm_memory_slot *memslot;
> + unsigned long gfn, hva, pa, psize = PAGE_SHIFT;
> + unsigned int shift;
> + pte_t *ptep, pte;
> +
> + /* Find the memslot for this address */
> + gfn = gpa >> PAGE_SHIFT;
> + memslot = __gfn_to_memslot(kvm_memslots_raw(kvm), gfn);
> + if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID))
> + return H_PARAMETER;
> +
> + /* Translate to host virtual address */
> + hva = __gfn_to_hva_memslot(memslot, gfn);
> +
> + /* Try to find the host pte for that virtual address */
> + ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift);
> + if (!ptep)
> + return H_TOO_HARD;
> + pte = kvmppc_read_update_linux_pte(ptep, writing);
> + if (!pte_present(pte))
> + return H_TOO_HARD;
> +
> + /* Convert to a physical address */
> + if (shift)
> + psize = 1UL << shift;
> + pa = pte_pfn(pte) << PAGE_SHIFT;
> + pa |= hva & (psize - 1);
> + pa |= gpa & ~PAGE_MASK;
> +
> + if (hpa)
> + *hpa = pa;
hpa is always not null.
> + if (memslot_p)
> + *memslot_p = memslot;
memslot_p!=NULL only when writing==1, you can safely drop the writing
parameter.
> +
> + return H_SUCCESS;
> +}
> +
> +static int kvmppc_do_h_page_init_zero(struct kvm_vcpu *vcpu, unsigned long dest)
> +{
> + struct kvm *kvm = vcpu->kvm;
> + struct kvm_memory_slot *memslot;
> + unsigned long pa;
> + unsigned long mmu_seq;
Nit: the two lines above can be one.
> + int i, ret = H_SUCCESS;
> +
> + /* Used later to detect if we might have been invalidated */
> + mmu_seq = kvm->mmu_notifier_seq;
> + smp_rmb();
> +
> + ret = kvmppc_get_hpa(vcpu, dest, 1, &pa, &memslot);
> + if (ret != H_SUCCESS)
> + return ret;
> +
> + /* Check if we've been invalidated */
> + spin_lock(&kvm->mmu_lock);
> + if (mmu_notifier_retry(kvm, mmu_seq)) {
> + ret = H_TOO_HARD;
> + goto out_unlock;
> + }
> +
> + /* Zero the page */
> + for (i = 0; i < 4096; i += L1_CACHE_BYTES, pa += L1_CACHE_BYTES)
> + dcbz((void *)pa);
> + kvmppc_update_dirty_map(memslot, dest >> PAGE_SHIFT, PAGE_SIZE);
> +
> +out_unlock:
> + spin_unlock(&kvm->mmu_lock);
> + return ret;
> +}
> +
> +static int kvmppc_do_h_page_init_copy(struct kvm_vcpu *vcpu, unsigned long dest,
> + unsigned long src)
> +{
> + struct kvm *kvm = vcpu->kvm;
> + struct kvm_memory_slot *dest_memslot;
> + unsigned long dest_pa, src_pa;
> + unsigned long mmu_seq;
> + int ret = H_SUCCESS;
> +
> + /* Used later to detect if we might have been invalidated */
> + mmu_seq = kvm->mmu_notifier_seq;
> + smp_rmb();
> +
> + ret = kvmppc_get_hpa(vcpu, dest, 1, &dest_pa, &dest_memslot);
> + if (ret != H_SUCCESS)
> + return ret;
> + ret = kvmppc_get_hpa(vcpu, src, 0, &src_pa, NULL);
> + if (ret != H_SUCCESS)
> + return ret;
> +
> + /* Check if we've been invalidated */
> + spin_lock(&kvm->mmu_lock);
I am no expect on spin_lock but from my memory in real mode it should be
at least raw_spin_lock as CONFIG_DEBUG_SPINLOCK (when defined) can break
things horribly.
> + if (mmu_notifier_retry(kvm, mmu_seq)) {
> + ret = H_TOO_HARD;
> + goto out_unlock;
> + }
> +
> + /* Copy the page */
> + memcpy((void *)dest_pa, (void *)src_pa, 4096);
s/4096/SZ_4K/
> +
> + kvmppc_update_dirty_map(dest_memslot, dest >> PAGE_SHIFT, PAGE_SIZE);
> +
> +out_unlock:
> + spin_unlock(&kvm->mmu_lock);
> + return ret;
> +}
> +
> +long kvmppc_rm_h_page_init(struct kvm_vcpu *vcpu, unsigned long flags,
> + unsigned long dest, unsigned long src)
> +{
> + struct kvm *kvm = vcpu->kvm;
> + u64 pg_sz = 1UL << 12; /* 4K page size */
> + u64 pg_mask = pg_sz - 1;
Same comment about SZ_4K as in 2/3.
> + int ret = H_SUCCESS;
Usually H_SUCCESS/... codes are long and EINVAL/... are int. Same for
2/3. The rule is not used 100% of time but nevertheless.
> +
> + /* Don't handle radix mode here, go up to the virtual mode handler */
> + if (kvm_is_radix(kvm))
> + return H_TOO_HARD;
> +
> + /* Check for invalid flags (H_PAGE_SET_LOANED covers all CMO flags) */
> + if (flags & ~(H_ICACHE_INVALIDATE | H_ICACHE_SYNCHRONIZE |
> + H_ZERO_PAGE | H_COPY_PAGE | H_PAGE_SET_LOANED))
> + return H_PARAMETER;
> +
> + /* dest (and src if copy_page flag set) must be page aligned */
> + if ((dest & pg_mask) || ((flags & H_COPY_PAGE) && (src & pg_mask)))
> + return H_PARAMETER;
> +
> + /* zero and/or copy the page as determined by the flags */
> + if (flags & H_ZERO_PAGE)
> + ret = kvmppc_do_h_page_init_zero(vcpu, dest);
"else" here?
> + if (flags & H_COPY_PAGE)
> + ret = kvmppc_do_h_page_init_copy(vcpu, dest, src);
else if (src)
return H_PARAMETER;
> +
> + /* We can ignore the other flags */
> +
> + return ret;
> +}
> +
> void kvmppc_invalidate_hpte(struct kvm *kvm, __be64 *hptep,
> unsigned long pte_index)
> {
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 9b8d50a7cbaf..5927497e7bbf 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -2268,7 +2268,7 @@ hcall_real_table:
> .long DOTSYM(kvmppc_rm_h_put_tce) - hcall_real_table
> .long 0 /* 0x24 - H_SET_SPRG0 */
> .long DOTSYM(kvmppc_h_set_dabr) - hcall_real_table
> - .long 0 /* 0x2c */
> + .long DOTSYM(kvmppc_rm_h_page_init) - hcall_real_table
> .long 0 /* 0x30 */
> .long 0 /* 0x34 */
> .long 0 /* 0x38 */
>
--
Alexey
