Commit 68f60510 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

Merge tag 'kvm-s390-next-6.18-1' of... 

Merge tag 'kvm-s390-next-6.18-1' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: A bugfix and a performance improvement

* Improve interrupt cpu for wakeup, change the heuristic to decide wich
  vCPU to deliver a floating interrupt to.
* Clear the pte when discarding a swapped page because of CMMA; this
  bug was introduced in 6.16 when refactoring gmap code.
parents a6ad5413 5deafa27

arch/s390/include/asm/kvm_host.h

+1 −1
Original line number Diff line number Diff line
@@ -356,7 +356,7 @@ struct kvm_s390_float_interrupt { 
	int counters[FIRQ_MAX_COUNT];

	struct kvm_s390_mchk_info mchk;

	struct kvm_s390_ext_info srv_signal;

	int next_rr_cpu;

	int last_sleep_cpu;

	struct mutex ais_lock;

	u8 simm;

	u8 nimm;

arch/s390/include/asm/pgtable.h

+22 −0
Original line number Diff line number Diff line
@@ -2055,4 +2055,26 @@ static inline unsigned long gmap_pgste_get_pgt_addr(unsigned long *pgt) 
	return res;

}



static inline pgste_t pgste_get_lock(pte_t *ptep)

{

	unsigned long value = 0;

#ifdef CONFIG_PGSTE

	unsigned long *ptr = (unsigned long *)(ptep + PTRS_PER_PTE);



	do {

		value = __atomic64_or_barrier(PGSTE_PCL_BIT, ptr);

	} while (value & PGSTE_PCL_BIT);

	value |= PGSTE_PCL_BIT;

#endif

	return __pgste(value);

}



static inline void pgste_set_unlock(pte_t *ptep, pgste_t pgste)

{

#ifdef CONFIG_PGSTE

	barrier();

	WRITE_ONCE(*(unsigned long *)(ptep + PTRS_PER_PTE), pgste_val(pgste) & ~PGSTE_PCL_BIT);

#endif

}



#endif /* _S390_PAGE_H */

arch/s390/kvm/interrupt.c

+9 −11
Original line number Diff line number Diff line
@@ -1323,6 +1323,7 @@ int kvm_s390_handle_wait(struct kvm_vcpu *vcpu) 
	VCPU_EVENT(vcpu, 4, "enabled wait: %llu ns", sltime);

no_timer:

	kvm_vcpu_srcu_read_unlock(vcpu);

	vcpu->kvm->arch.float_int.last_sleep_cpu = vcpu->vcpu_idx;

	kvm_vcpu_halt(vcpu);

	vcpu->valid_wakeup = false;

	__unset_cpu_idle(vcpu);
@@ -1949,18 +1950,15 @@ static void __floating_irq_kick(struct kvm *kvm, u64 type) 
	if (!online_vcpus)

		return;



	/* find idle VCPUs first, then round robin */

	sigcpu = find_first_bit(kvm->arch.idle_mask, online_vcpus);

	if (sigcpu == online_vcpus) {

		do {

			sigcpu = kvm->arch.float_int.next_rr_cpu++;

			kvm->arch.float_int.next_rr_cpu %= online_vcpus;

	for (sigcpu = kvm->arch.float_int.last_sleep_cpu; ; sigcpu++) {

		sigcpu %= online_vcpus;

		dst_vcpu = kvm_get_vcpu(kvm, sigcpu);

		if (!is_vcpu_stopped(dst_vcpu))

			break;

		/* avoid endless loops if all vcpus are stopped */

		if (nr_tries++ >= online_vcpus)

			return;

		} while (is_vcpu_stopped(kvm_get_vcpu(kvm, sigcpu)));

	}

	dst_vcpu = kvm_get_vcpu(kvm, sigcpu);



	/* make the VCPU drop out of the SIE, or wake it up if sleeping */

	switch (type) {

arch/s390/mm/gmap_helpers.c

+11 −1
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/pagewalk.h>

#include <linux/ksm.h>

#include <asm/gmap_helpers.h>

#include <asm/pgtable.h>



/**

 * ptep_zap_swap_entry() - discard a swap entry.
@@ -47,6 +48,7 @@ void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr) 
{

	struct vm_area_struct *vma;

	spinlock_t *ptl;

	pgste_t pgste;

	pte_t *ptep;



	mmap_assert_locked(mm);
@@ -60,8 +62,16 @@ void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr) 
	ptep = get_locked_pte(mm, vmaddr, &ptl);

	if (unlikely(!ptep))

		return;

	if (pte_swap(*ptep))

	if (pte_swap(*ptep)) {

		preempt_disable();

		pgste = pgste_get_lock(ptep);



		ptep_zap_swap_entry(mm, pte_to_swp_entry(*ptep));

		pte_clear(mm, vmaddr, ptep);



		pgste_set_unlock(ptep, pgste);

		preempt_enable();

	}

	pte_unmap_unlock(ptep, ptl);

}

EXPORT_SYMBOL_GPL(gmap_helper_zap_one_page);

arch/s390/mm/pgtable.c

+1 −22
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <asm/tlbflush.h>

#include <asm/mmu_context.h>

#include <asm/page-states.h>

#include <asm/pgtable.h>

#include <asm/machine.h>



pgprot_t pgprot_writecombine(pgprot_t prot)
@@ -115,28 +116,6 @@ static inline pte_t ptep_flush_lazy(struct mm_struct *mm, 
	return old;

}



static inline pgste_t pgste_get_lock(pte_t *ptep)

{

	unsigned long value = 0;

#ifdef CONFIG_PGSTE

	unsigned long *ptr = (unsigned long *)(ptep + PTRS_PER_PTE);



	do {

		value = __atomic64_or_barrier(PGSTE_PCL_BIT, ptr);

	} while (value & PGSTE_PCL_BIT);

	value |= PGSTE_PCL_BIT;

#endif

	return __pgste(value);

}



static inline void pgste_set_unlock(pte_t *ptep, pgste_t pgste)

{

#ifdef CONFIG_PGSTE

	barrier();

	WRITE_ONCE(*(unsigned long *)(ptep + PTRS_PER_PTE), pgste_val(pgste) & ~PGSTE_PCL_BIT);

#endif

}



static inline pgste_t pgste_get(pte_t *ptep)

{

	unsigned long pgste = 0;