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

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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: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Paul Mackerras 2013-04-18 19:50:24 +00:00 committed by Alexander Graf
parent d9ce6041b3
commit a1b4a0f606
3 changed files with 63 additions and 20 deletions
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13
arch/powerpc/include/asm/kvm_book3s_64.h
View File

@ -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__ */

59
arch/powerpc/kvm/book3s_64_mmu_hv.c
View File

@ -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;
rev[i].guest_rpte = ptel | rcbits;
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);
rev[i].guest_rpte |= HPTE_R_R;
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;
rev[i].guest_rpte |= HPTE_R_C;
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;

11
arch/powerpc/kvm/book3s_hv_rm_mmu.c
View File

@ -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,