[PATCH 5/7] KVM: arm64: Add memory_slot_unmaped counter for kvm_stat

[Yoan Picchi]

Add a counter for when a memory slot is unmapped, meaning that all
memory belonging to a specific VM is made available to be mapped for
anoother VM. A memory slot is the memory that can be used to hold a
guest's pages and can be made available by Qemu for instance. For
now the memory slot are only unmapped when a vm restarts.

Signed-off-by: Yoan Picchi <yoan.picchi at arm.com>
---
 arch/arm64/include/asm/kvm_host.h | 1 +
 arch/arm64/kvm/guest.c            | 1 +
 arch/arm64/kvm/mmu.c              | 1 +
 3 files changed, 3 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e6967951f..76c81aa79 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -548,6 +548,7 @@ static inline bool __vcpu_write_sys_reg_to_cpu(u64 val, int reg)
 struct kvm_vm_stat {
 	ulong remote_tlb_flush;
 	ulong flush_all_cache_lines;
+	ulong memory_slot_unmaped;
 	ulong cached_page_invalidated;
 };
 
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index d948c3bd2..cd227136e 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -42,6 +42,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
 	VCPU_STAT("huge_page_mapped", huge_page_mapped),
 	VM_STAT("remote_tlb_flush", remote_tlb_flush),
 	VM_STAT("flush_all_cache_lines", flush_all_cache_lines),
+	VM_STAT("memory_slot_unmaped", memory_slot_unmaped),
 	VM_STAT("cached_page_invalidated", cached_page_invalidated),
 	VCPU_STAT("exits", exits),
 	VCPU_STAT("halt_poll_success_ns", halt_poll_success_ns),
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 985b048df..1e8aeafc2 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -419,6 +419,7 @@ static void stage2_unmap_memslot(struct kvm *kvm,
 	phys_addr_t addr = memslot->base_gfn << PAGE_SHIFT;
 	phys_addr_t size = PAGE_SIZE * memslot->npages;
 	hva_t reg_end = hva + size;
+	kvm->stat.memory_slot_unmaped++;
 
 	/*
 	 * A memory region could potentially cover multiple VMAs, and any holes
-- 
2.17.1