On Sun, Aug 19, 2012 at 9:00 AM, Avi Kivity [off-list ref] wrote:

On 08/19/2012 12:38 PM, Peter Maydell wrote:

quoted

On 19 August 2012 05:34, Christoffer Dall [off-list ref] wrote:

quoted

On Thu, Aug 16, 2012 at 2:25 PM, Alexander Graf [off-list ref] wrote:

quoted

A single hva can have multiple gpas mapped, no? At least that's what I gathered
from the discussion about my attempt to a function similar to this :).

quoted

I don't think this is the case for ARM, can you provide an example? We
use gfn_to_pfn_prot and only allow user memory regions. What you
suggest would be multiple physical addresses pointing to the same
memory bank, I don't think that makes any sense on ARM hardware, for
x86 and PPC I don't know.

I don't know what an hva is,

host virtual address

(see Documentation/virtual/kvm/mmu.txt for more TLAs in this area).

 but yes, ARM boards can have the same

quoted

block of RAM aliased into multiple places in the physical address space.
(we don't currently bother to implement the aliases in qemu's vexpress-a15
though because it's a bunch of mappings of the low 2GB into high
addresses mostly intended to let you test LPAE code without having to
put lots of RAM on the hardware).

I stand corrected.

Even if it weren't common, the API allows it, so we must behave sensibly.

true, this should be a solution:

commit 2a8661fd7e6c15889a20a4547bd7861e84b778a8
Author: Christoffer Dall [off-list ref]
Date:   Sun Aug 19 15:52:10 2012 -0400

    KVM: ARM: A single hva can map multiple gpas

    Handle mmu notifier ops for every such mapping.

    Signed-off-by: Christoffer Dall [off-list ref]

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 3df4fa8..9b23230 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c

@@ -754,11 +754,14 @@ int kvm_handle_guest_abort(struct kvm_vcpu

*vcpu, struct kvm_run *run)
 	return ret ? ret : 1;
 }

-static bool hva_to_gpa(struct kvm *kvm, unsigned long hva, gpa_t *gpa)
+static int handle_hva_to_gpa(struct kvm *kvm, unsigned long hva,
+			     void (*handler)(struct kvm *kvm, unsigned long hva,
+					     gpa_t gpa, void *data),
+			     void *data)
 {
 	struct kvm_memslots *slots;
 	struct kvm_memory_slot *memslot;
-	bool found = false;
+	int cnt = 0;

 	slots = kvm_memslots(kvm);

@@ -769,31 +772,36 @@ static bool hva_to_gpa(struct kvm *kvm, unsigned

long hva, gpa_t *gpa)

 		end = start + (memslot->npages << PAGE_SHIFT);
 		if (hva >= start && hva < end) {
+			gpa_t gpa;
 			gpa_t gpa_offset = hva - start;
-			*gpa = (memslot->base_gfn << PAGE_SHIFT) + gpa_offset;
-			found = true;
-			/* no overlapping memslots allowed: break */
-			break;
+			gpa = (memslot->base_gfn << PAGE_SHIFT) + gpa_offset;
+			handler(kvm, hva, gpa, data);
+			cnt++;
 		}
 	}

-	return found;
+	return cnt;
+}
+
+static void kvm_unmap_hva_handler(struct kvm *kvm, unsigned long hva,
+				  gpa_t gpa, void *data)
+{
+	spin_lock(&kvm->arch.pgd_lock);
+	stage2_clear_pte(kvm, gpa);
+	spin_unlock(&kvm->arch.pgd_lock);
 }

 int kvm_unmap_hva(struct kvm *kvm, unsigned long hva)
 {
-	bool found;
-	gpa_t gpa;
+	int found;

 	if (!kvm->arch.pgd)
 		return 0;

-	found = hva_to_gpa(kvm, hva, &gpa);
-	if (found) {
-		spin_lock(&kvm->arch.pgd_lock);
-		stage2_clear_pte(kvm, gpa);
-		spin_unlock(&kvm->arch.pgd_lock);
-	}
+	found = handle_hva_to_gpa(kvm, hva, &kvm_unmap_hva_handler, NULL);
+	if (found > 0)
+		__kvm_tlb_flush_vmid(kvm);
+
 	return 0;
 }

@@ -814,21 +822,27 @@ int kvm_unmap_hva_range(struct kvm *kvm,
 	return 0;
 }

+static void kvm_set_spte_handler(struct kvm *kvm, unsigned long hva,
+				 gpa_t gpa, void *data)
+{
+	pte_t *pte = (pte_t *)data;
+
+	spin_lock(&kvm->arch.pgd_lock);
+	stage2_set_pte(kvm, NULL, gpa, pte);
+	spin_unlock(&kvm->arch.pgd_lock);
+}
+
+
 void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
 {
-	gpa_t gpa;
-	bool found;
+	int found;

 	if (!kvm->arch.pgd)
 		return;

-	found = hva_to_gpa(kvm, hva, &gpa);
-	if (found) {
-		spin_lock(&kvm->arch.pgd_lock);
-		stage2_set_pte(kvm, NULL, gpa, &pte);
-		spin_unlock(&kvm->arch.pgd_lock);
+	found = handle_hva_to_gpa(kvm, hva, &kvm_set_spte_handler, &pte);
+	if (found > 0)
 		__kvm_tlb_flush_vmid(kvm);
-	}
 }

 void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu)

--