[PATCH v2 2/2] KVM: remove KVM host pv mmu support

[Chris Wright <chrisw@sous-sol.org>]

The host side pv mmu support has been marked for feature removal in
January 2011.  It's not in use, is slower than shadow or hardware
assisted paging, and a maintenance burden.  It's November 2011, time to
remove it.

Signed-off-by: Chris Wright <chrisw@redhat.com>
---

- v2 rebase to b796a09c

 Documentation/feature-removal-schedule.txt |    9 --
 arch/x86/include/asm/kvm_host.h            |   13 ---
 arch/x86/kvm/mmu.c                         |  135 ----------------------------
 arch/x86/kvm/x86.c                         |   12 ---
 4 files changed, 0 insertions(+), 169 deletions(-)

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index d5ac362..877f897 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -397,15 +397,6 @@ Who: 	anybody or Florian Mickler <florian@mickler.org>
 
 ----------------------------
 
-What:	KVM paravirt mmu host support
-When:	January 2011
-Why:	The paravirt mmu host support is slower than non-paravirt mmu, both
-	on newer and older hardware.  It is already not exposed to the guest,
-	and kept only for live migration purposes.
-Who:	Avi Kivity <avi@redhat.com>
-
-----------------------------
-
 What:	iwlwifi 50XX module parameters
 When:	3.0
 Why:	The "..50" modules parameters were used to configure 5000 series and
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c1f19de..6d83264 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -244,13 +244,6 @@ struct kvm_mmu_page {
 	struct rcu_head rcu;
 };
 
-struct kvm_pv_mmu_op_buffer {
-	void *ptr;
-	unsigned len;
-	unsigned processed;
-	char buf[512] __aligned(sizeof(long));
-};
-
 struct kvm_pio_request {
 	unsigned long count;
 	int in;
@@ -347,10 +340,6 @@ struct kvm_vcpu_arch {
 	 */
 	struct kvm_mmu *walk_mmu;
 
-	/* only needed in kvm_pv_mmu_op() path, but it's hot so
-	 * put it here to avoid allocation */
-	struct kvm_pv_mmu_op_buffer mmu_op_buffer;
-
 	struct kvm_mmu_memory_cache mmu_pte_list_desc_cache;
 	struct kvm_mmu_memory_cache mmu_page_cache;
 	struct kvm_mmu_memory_cache mmu_page_header_cache;
@@ -667,8 +656,6 @@ int load_pdptrs(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, unsigned long cr3);
 
 int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
 			  const void *val, int bytes);
-int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
-		  gpa_t addr, unsigned long *ret);
 u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn);
 
 extern bool tdp_enabled;
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index e9534ce..a9b3a32 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2028,20 +2028,6 @@ int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page);
 
-static void mmu_unshadow(struct kvm *kvm, gfn_t gfn)
-{
-	struct kvm_mmu_page *sp;
-	struct hlist_node *node;
-	LIST_HEAD(invalid_list);
-
-	for_each_gfn_indirect_valid_sp(kvm, sp, gfn, node) {
-		pgprintk("%s: zap %llx %x\n",
-			 __func__, gfn, sp->role.word);
-		kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
-	}
-	kvm_mmu_commit_zap_page(kvm, &invalid_list);
-}
-
 static void page_header_update_slot(struct kvm *kvm, void *pte, gfn_t gfn)
 {
 	int slot = memslot_id(kvm, gfn);
@@ -4004,127 +3990,6 @@ unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm)
 	return nr_mmu_pages;
 }
 
-static void *pv_mmu_peek_buffer(struct kvm_pv_mmu_op_buffer *buffer,
-				unsigned len)
-{
-	if (len > buffer->len)
-		return NULL;
-	return buffer->ptr;
-}
-
-static void *pv_mmu_read_buffer(struct kvm_pv_mmu_op_buffer *buffer,
-				unsigned len)
-{
-	void *ret;
-
-	ret = pv_mmu_peek_buffer(buffer, len);
-	if (!ret)
-		return ret;
-	buffer->ptr += len;
-	buffer->len -= len;
-	buffer->processed += len;
-	return ret;
-}
-
-static int kvm_pv_mmu_write(struct kvm_vcpu *vcpu,
-			     gpa_t addr, gpa_t value)
-{
-	int bytes = 8;
-	int r;
-
-	if (!is_long_mode(vcpu) && !is_pae(vcpu))
-		bytes = 4;
-
-	r = mmu_topup_memory_caches(vcpu);
-	if (r)
-		return r;
-
-	if (!emulator_write_phys(vcpu, addr, &value, bytes))
-		return -EFAULT;
-
-	return 1;
-}
-
-static int kvm_pv_mmu_flush_tlb(struct kvm_vcpu *vcpu)
-{
-	(void)kvm_set_cr3(vcpu, kvm_read_cr3(vcpu));
-	return 1;
-}
-
-static int kvm_pv_mmu_release_pt(struct kvm_vcpu *vcpu, gpa_t addr)
-{
-	spin_lock(&vcpu->kvm->mmu_lock);
-	mmu_unshadow(vcpu->kvm, addr >> PAGE_SHIFT);
-	spin_unlock(&vcpu->kvm->mmu_lock);
-	return 1;
-}
-
-static int kvm_pv_mmu_op_one(struct kvm_vcpu *vcpu,
-			     struct kvm_pv_mmu_op_buffer *buffer)
-{
-	struct kvm_mmu_op_header *header;
-
-	header = pv_mmu_peek_buffer(buffer, sizeof *header);
-	if (!header)
-		return 0;
-	switch (header->op) {
-	case KVM_MMU_OP_WRITE_PTE: {
-		struct kvm_mmu_op_write_pte *wpte;
-
-		wpte = pv_mmu_read_buffer(buffer, sizeof *wpte);
-		if (!wpte)
-			return 0;
-		return kvm_pv_mmu_write(vcpu, wpte->pte_phys,
-					wpte->pte_val);
-	}
-	case KVM_MMU_OP_FLUSH_TLB: {
-		struct kvm_mmu_op_flush_tlb *ftlb;
-
-		ftlb = pv_mmu_read_buffer(buffer, sizeof *ftlb);
-		if (!ftlb)
-			return 0;
-		return kvm_pv_mmu_flush_tlb(vcpu);
-	}
-	case KVM_MMU_OP_RELEASE_PT: {
-		struct kvm_mmu_op_release_pt *rpt;
-
-		rpt = pv_mmu_read_buffer(buffer, sizeof *rpt);
-		if (!rpt)
-			return 0;
-		return kvm_pv_mmu_release_pt(vcpu, rpt->pt_phys);
-	}
-	default: return 0;
-	}
-}
-
-int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
-		  gpa_t addr, unsigned long *ret)
-{
-	int r;
-	struct kvm_pv_mmu_op_buffer *buffer = &vcpu->arch.mmu_op_buffer;
-
-	buffer->ptr = buffer->buf;
-	buffer->len = min_t(unsigned long, bytes, sizeof buffer->buf);
-	buffer->processed = 0;
-
-	r = kvm_read_guest(vcpu->kvm, addr, buffer->buf, buffer->len);
-	if (r)
-		goto out;
-
-	while (buffer->len) {
-		r = kvm_pv_mmu_op_one(vcpu, buffer);
-		if (r < 0)
-			goto out;
-		if (r == 0)
-			break;
-	}
-
-	r = 1;
-out:
-	*ret = buffer->processed;
-	return r;
-}
-
 int kvm_mmu_get_spte_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 sptes[4])
 {
 	struct kvm_shadow_walk_iterator iterator;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2b1c526..3fb9757 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5273,15 +5273,6 @@ int kvm_emulate_halt(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvm_emulate_halt);
 
-static inline gpa_t hc_gpa(struct kvm_vcpu *vcpu, unsigned long a0,
-			   unsigned long a1)
-{
-	if (is_long_mode(vcpu))
-		return a0;
-	else
-		return a0 | ((gpa_t)a1 << 32);
-}
-
 int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 {
 	u64 param, ingpa, outgpa, ret;
@@ -5377,9 +5368,6 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 	case KVM_HC_VAPIC_POLL_IRQ:
 		ret = 0;
 		break;
-	case KVM_HC_MMU_OP:
-		r = kvm_pv_mmu_op(vcpu, a0, hc_gpa(vcpu, a1, a2), &ret);
-		break;
 	default:
 		ret = -KVM_ENOSYS;
 		break;