| Message ID | 20200206030900.147032-8-leonardo@linux.ibm.com |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | Introduces new functions for tracking lockless pagetable walks | expand |
Le 06/02/2020 à 04:08, Leonardo Bras a écrit : > Applies the new functions used for tracking lockless pgtable walks on > kvmppc_e500_shadow_map(). > > Fixes the place where local_irq_restore() is called: previously, if ptep > was NULL, local_irq_restore() would never be called. > > local_irq_{save,restore} is already inside {begin,end}_lockless_pgtbl_walk, > so there is no need to repeat it here. > > Variable that saves the irq mask was renamed from flags to irq_mask so it > doesn't lose meaning now it's not directly passed to local_irq_* functions. > > Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> > --- > arch/powerpc/kvm/e500_mmu_host.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c > index 425d13806645..3dcf11f77256 100644 > --- a/arch/powerpc/kvm/e500_mmu_host.c > +++ b/arch/powerpc/kvm/e500_mmu_host.c > @@ -336,7 +336,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, > pte_t *ptep; > unsigned int wimg = 0; > pgd_t *pgdir; > - unsigned long flags; > + unsigned long irq_mask; > > /* used to check for invalidations in progress */ > mmu_seq = kvm->mmu_notifier_seq; > @@ -473,7 +473,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, > * We are holding kvm->mmu_lock so a notifier invalidate > * can't run hence pfn won't change. > */ > - local_irq_save(flags); > + irq_mask = begin_lockless_pgtbl_walk(); > ptep = find_linux_pte(pgdir, hva, NULL, NULL); > if (ptep) { > pte_t pte = READ_ONCE(*ptep); > @@ -481,15 +481,16 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, > if (pte_present(pte)) { > wimg = (pte_val(pte) >> PTE_WIMGE_SHIFT) & > MAS2_WIMGE_MASK; > - local_irq_restore(flags); > } else { > - local_irq_restore(flags); > + end_lockless_pgtbl_walk(irq_mask); > pr_err_ratelimited("%s: pte not present: gfn %lx,pfn %lx\n", > __func__, (long)gfn, pfn); > ret = -EINVAL; > goto out; > } > } > + end_lockless_pgtbl_walk(irq_mask); > + I don't really like unbalanced begin/end. Something like the following would be cleaner: begin_lockless_pgtbl_walk() ptep = find() if (ptep) { pte = READ_ONCE() if (pte_present(pte)) wing= else ret = -EINVAL; } end_lockless_pgtbl_walk() if (ret) { pr_err_rate...() goto out; } > kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg); > > kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize, > Christophe
Hello Christophe, On Thu, 2020-02-06 at 07:18 +0100, Christophe Leroy wrote: > > I don't really like unbalanced begin/end. > > Something like the following would be cleaner: > > > begin_lockless_pgtbl_walk() > ptep = find() > if (ptep) { > pte = READ_ONCE() > if (pte_present(pte)) > wing= > else > ret = -EINVAL; > } > end_lockless_pgtbl_walk() > > if (ret) { > pr_err_rate...() > goto out; > } > > Sure, looks better that way. I will change that for v7. Thanks for the feedback, Leonardo Bras
diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c index 425d13806645..3dcf11f77256 100644 --- a/arch/powerpc/kvm/e500_mmu_host.c +++ b/arch/powerpc/kvm/e500_mmu_host.c @@ -336,7 +336,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, pte_t *ptep; unsigned int wimg = 0; pgd_t *pgdir; - unsigned long flags; + unsigned long irq_mask; /* used to check for invalidations in progress */ mmu_seq = kvm->mmu_notifier_seq; @@ -473,7 +473,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, * We are holding kvm->mmu_lock so a notifier invalidate * can't run hence pfn won't change. */ - local_irq_save(flags); + irq_mask = begin_lockless_pgtbl_walk(); ptep = find_linux_pte(pgdir, hva, NULL, NULL); if (ptep) { pte_t pte = READ_ONCE(*ptep); @@ -481,15 +481,16 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, if (pte_present(pte)) { wimg = (pte_val(pte) >> PTE_WIMGE_SHIFT) & MAS2_WIMGE_MASK; - local_irq_restore(flags); } else { - local_irq_restore(flags); + end_lockless_pgtbl_walk(irq_mask); pr_err_ratelimited("%s: pte not present: gfn %lx,pfn %lx\n", __func__, (long)gfn, pfn); ret = -EINVAL; goto out; } } + end_lockless_pgtbl_walk(irq_mask); + kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg); kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize,
Applies the new functions used for tracking lockless pgtable walks on kvmppc_e500_shadow_map(). Fixes the place where local_irq_restore() is called: previously, if ptep was NULL, local_irq_restore() would never be called. local_irq_{save,restore} is already inside {begin,end}_lockless_pgtbl_walk, so there is no need to repeat it here. Variable that saves the irq mask was renamed from flags to irq_mask so it doesn't lose meaning now it's not directly passed to local_irq_* functions. Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> --- arch/powerpc/kvm/e500_mmu_host.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)