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Subject[PATCH 45/50] KVM: MMU: Add rmap_next(), a helper for walking kvm rmaps
Date
From: Izik Eidus <izike@qumranet.com>

Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
drivers/kvm/mmu.c | 45 +++++++++++++++++++++++++++++++++++----------
1 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index f52604a..14e54e3 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -456,28 +456,53 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
}
}

-static void rmap_write_protect(struct kvm *kvm, u64 gfn)
+static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte)
{
struct kvm_rmap_desc *desc;
+ struct kvm_rmap_desc *prev_desc;
+ u64 *prev_spte;
+ int i;
+
+ if (!*rmapp)
+ return NULL;
+ else if (!(*rmapp & 1)) {
+ if (!spte)
+ return (u64 *)*rmapp;
+ return NULL;
+ }
+ desc = (struct kvm_rmap_desc *)(*rmapp & ~1ul);
+ prev_desc = NULL;
+ prev_spte = NULL;
+ while (desc) {
+ for (i = 0; i < RMAP_EXT && desc->shadow_ptes[i]; ++i) {
+ if (prev_spte == spte)
+ return desc->shadow_ptes[i];
+ prev_spte = desc->shadow_ptes[i];
+ }
+ desc = desc->more;
+ }
+ return NULL;
+}
+
+static void rmap_write_protect(struct kvm *kvm, u64 gfn)
+{
unsigned long *rmapp;
u64 *spte;
+ u64 *prev_spte;

gfn = unalias_gfn(kvm, gfn);
rmapp = gfn_to_rmap(kvm, gfn);

- while (*rmapp) {
- if (!(*rmapp & 1))
- spte = (u64 *)*rmapp;
- else {
- desc = (struct kvm_rmap_desc *)(*rmapp & ~1ul);
- spte = desc->shadow_ptes[0];
- }
+ spte = rmap_next(kvm, rmapp, NULL);
+ while (spte) {
BUG_ON(!spte);
BUG_ON(!(*spte & PT_PRESENT_MASK));
BUG_ON(!(*spte & PT_WRITABLE_MASK));
rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
- rmap_remove(kvm, spte);
- set_shadow_pte(spte, *spte & ~PT_WRITABLE_MASK);
+ prev_spte = spte;
+ spte = rmap_next(kvm, rmapp, spte);
+ rmap_remove(kvm, prev_spte);
+ set_shadow_pte(prev_spte, *prev_spte & ~PT_WRITABLE_MASK);
kvm_flush_remote_tlbs(kvm);
}
}
--
1.5.3.7


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