Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a1b4a0f6 authored by Paul Mackerras's avatar Paul Mackerras Committed by Alexander Graf
Browse files

KVM: PPC: Book3S HV: Make HPT reading code notice R/C bit changes 



At present, the code that determines whether a HPT entry has changed,
and thus needs to be sent to userspace when it is copying the HPT,
doesn't consider a hardware update to the reference and change bits
(R and C) in the HPT entries to constitute a change that needs to
be sent to userspace.  This adds code to check for changes in R and C
when we are scanning the HPT to find changed entries, and adds code
to set the changed flag for the HPTE when we update the R and C bits
in the guest view of the HPTE.

Since we now need to set the HPTE changed flag in book3s_64_mmu_hv.c
as well as book3s_hv_rm_mmu.c, we move the note_hpte_modification()
function into kvm_book3s_64.h.

Current Linux guest kernels don't use the hardware updates of R and C
in the HPT, so this change won't affect them.  Linux (or other) kernels
might in future want to use the R and C bits and have them correctly
transferred across when a guest is migrated, so it is better to correct
this deficiency.

Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
parent d9ce6041

arch/powerpc/include/asm/kvm_book3s_64.h

+13 −0
Original line number Diff line number Diff line
@@ -268,4 +268,17 @@ static inline int is_vrma_hpte(unsigned long hpte_v) 
		(HPTE_V_1TB_SEG | (VRMA_VSID << (40 - 16)));

}



#ifdef CONFIG_KVM_BOOK3S_64_HV

/*

 * Note modification of an HPTE; set the HPTE modified bit

 * if anyone is interested.

 */

static inline void note_hpte_modification(struct kvm *kvm,

					  struct revmap_entry *rev)

{

	if (atomic_read(&kvm->arch.hpte_mod_interest))

		rev->guest_rpte |= HPTE_GR_MODIFIED;

}

#endif /* CONFIG_KVM_BOOK3S_64_HV */



#endif /* __ASM_KVM_BOOK3S_64_H__ */

arch/powerpc/kvm/book3s_64_mmu_hv.c

+50 −9
Original line number Diff line number Diff line
@@ -893,7 +893,10 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp, 
			/* Harvest R and C */

			rcbits = hptep[1] & (HPTE_R_R | HPTE_R_C);

			*rmapp |= rcbits << KVMPPC_RMAP_RC_SHIFT;

			if (rcbits & ~rev[i].guest_rpte) {

				rev[i].guest_rpte = ptel | rcbits;

				note_hpte_modification(kvm, &rev[i]);

			}

		}

		unlock_rmap(rmapp);

		hptep[0] &= ~HPTE_V_HVLOCK;
@@ -976,7 +979,10 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp, 
		/* Now check and modify the HPTE */

		if ((hptep[0] & HPTE_V_VALID) && (hptep[1] & HPTE_R_R)) {

			kvmppc_clear_ref_hpte(kvm, hptep, i);

			if (!(rev[i].guest_rpte & HPTE_R_R)) {

				rev[i].guest_rpte |= HPTE_R_R;

				note_hpte_modification(kvm, &rev[i]);

			}

			ret = 1;

		}

		hptep[0] &= ~HPTE_V_HVLOCK;
@@ -1080,7 +1086,10 @@ static int kvm_test_clear_dirty(struct kvm *kvm, unsigned long *rmapp) 
			hptep[1] &= ~HPTE_R_C;

			eieio();

			hptep[0] = (hptep[0] & ~HPTE_V_ABSENT) | HPTE_V_VALID;

			if (!(rev[i].guest_rpte & HPTE_R_C)) {

				rev[i].guest_rpte |= HPTE_R_C;

				note_hpte_modification(kvm, &rev[i]);

			}

			ret = 1;

		}

		hptep[0] &= ~HPTE_V_HVLOCK;
@@ -1193,16 +1202,36 @@ struct kvm_htab_ctx { 


#define HPTE_SIZE	(2 * sizeof(unsigned long))



/*

 * Returns 1 if this HPT entry has been modified or has pending

 * R/C bit changes.

 */

static int hpte_dirty(struct revmap_entry *revp, unsigned long *hptp)

{

	unsigned long rcbits_unset;



	if (revp->guest_rpte & HPTE_GR_MODIFIED)

		return 1;



	/* Also need to consider changes in reference and changed bits */

	rcbits_unset = ~revp->guest_rpte & (HPTE_R_R | HPTE_R_C);

	if ((hptp[0] & HPTE_V_VALID) && (hptp[1] & rcbits_unset))

		return 1;



	return 0;

}



static long record_hpte(unsigned long flags, unsigned long *hptp,

			unsigned long *hpte, struct revmap_entry *revp,

			int want_valid, int first_pass)

{

	unsigned long v, r;

	unsigned long rcbits_unset;

	int ok = 1;

	int valid, dirty;



	/* Unmodified entries are uninteresting except on the first pass */

	dirty = !!(revp->guest_rpte & HPTE_GR_MODIFIED);

	dirty = hpte_dirty(revp, hptp);

	if (!first_pass && !dirty)

		return 0;
@@ -1223,16 +1252,28 @@ static long record_hpte(unsigned long flags, unsigned long *hptp, 
		while (!try_lock_hpte(hptp, HPTE_V_HVLOCK))

			cpu_relax();

		v = hptp[0];



		/* re-evaluate valid and dirty from synchronized HPTE value */

		valid = !!(v & HPTE_V_VALID);

		dirty = !!(revp->guest_rpte & HPTE_GR_MODIFIED);



		/* Harvest R and C into guest view if necessary */

		rcbits_unset = ~revp->guest_rpte & (HPTE_R_R | HPTE_R_C);

		if (valid && (rcbits_unset & hptp[1])) {

			revp->guest_rpte |= (hptp[1] & (HPTE_R_R | HPTE_R_C)) |

				HPTE_GR_MODIFIED;

			dirty = 1;

		}



		if (v & HPTE_V_ABSENT) {

			v &= ~HPTE_V_ABSENT;

			v |= HPTE_V_VALID;

			valid = 1;

		}

		/* re-evaluate valid and dirty from synchronized HPTE value */

		valid = !!(v & HPTE_V_VALID);

		if ((flags & KVM_GET_HTAB_BOLTED_ONLY) && !(v & HPTE_V_BOLTED))

			valid = 0;

		r = revp->guest_rpte | (hptp[1] & (HPTE_R_R | HPTE_R_C));

		dirty = !!(revp->guest_rpte & HPTE_GR_MODIFIED);



		r = revp->guest_rpte;

		/* only clear modified if this is the right sort of entry */

		if (valid == want_valid && dirty) {

			r &= ~HPTE_GR_MODIFIED;
@@ -1288,7 +1329,7 @@ static ssize_t kvm_htab_read(struct file *file, char __user *buf, 
		/* Skip uninteresting entries, i.e. clean on not-first pass */

		if (!first_pass) {

			while (i < kvm->arch.hpt_npte &&

			       !(revp->guest_rpte & HPTE_GR_MODIFIED)) {

			       !hpte_dirty(revp, hptp)) {

				++i;

				hptp += 2;

				++revp;

arch/powerpc/kvm/book3s_hv_rm_mmu.c

+0 −11
Original line number Diff line number Diff line
@@ -97,17 +97,6 @@ void kvmppc_add_revmap_chain(struct kvm *kvm, struct revmap_entry *rev, 
}

EXPORT_SYMBOL_GPL(kvmppc_add_revmap_chain);



/*

 * Note modification of an HPTE; set the HPTE modified bit

 * if anyone is interested.

 */

static inline void note_hpte_modification(struct kvm *kvm,

					  struct revmap_entry *rev)

{

	if (atomic_read(&kvm->arch.hpte_mod_interest))

		rev->guest_rpte |= HPTE_GR_MODIFIED;

}



/* Remove this HPTE from the chain for a real page */

static void remove_revmap_chain(struct kvm *kvm, long pte_index,

				struct revmap_entry *rev,