Date:   Wed, 19 Aug 2020 10:17:42 -0500
From:   eric van tassell <Eric.VanTassell@....com>
To:     kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, bp@...en8.de, hpa@...or.com,
        mingo@...hat.com, jmattson@...gle.com, joro@...tes.org,
        pbonzini@...hat.com, sean.j.christopherson@...el.com,
        tglx@...utronix.de, vkuznets@...hat.com, wanpengli@...cent.com,
        x86@...nel.org, rientjes@...gle.com, junaids@...gle.com,
        evantass@....com
Subject: [Patch v2 4/4] KVM:SVM: Remove struct enc_region and associated pinned page tracking.

Remove the enc_region structure definition and the code which maintained
it, as they are no longer needed in view of the xarray support we added in
the previous patch.

Leave svm_register_enc_region() and svm_unregister_enc_region() as stubs
since the ioctl is used by qemu and qemu will crash if they do not
return 0.

Co-developed-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: eric van tassell <Eric.VanTassell@....com>
---
 arch/x86/kvm/svm/sev.c | 117 +----------------------------------------
 arch/x86/kvm/svm/svm.h |   1 -
 2 files changed, 1 insertion(+), 117 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 4a0157254fef..635e15f01edb 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -27,14 +27,6 @@ static unsigned long *sev_asid_bitmap;
 static unsigned long *sev_reclaim_asid_bitmap;
 #define __sme_page_pa(x) __sme_set(page_to_pfn(x) << PAGE_SHIFT)
 
-struct enc_region {
-	struct list_head list;
-	unsigned long npages;
-	struct page **pages;
-	unsigned long uaddr;
-	unsigned long size;
-};
-
 static int sev_flush_asids(void)
 {
 	int ret, error = 0;
@@ -182,7 +174,6 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 
 	sev->active = true;
 	sev->asid = asid;
-	INIT_LIST_HEAD(&sev->regions_list);
 
 	xa_init(&sev->pages_xarray);
 
@@ -1074,113 +1065,18 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 int svm_register_enc_region(struct kvm *kvm,
 			    struct kvm_enc_region *range)
 {
-	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
-	struct enc_region *region;
-	int ret = 0;
-
-	if (!sev_guest(kvm))
-		return -ENOTTY;
-
-	if (range->addr > ULONG_MAX || range->size > ULONG_MAX)
-		return -EINVAL;
-
-	region = kzalloc(sizeof(*region), GFP_KERNEL_ACCOUNT);
-	if (!region)
-		return -ENOMEM;
-
-	region->pages = sev_pin_memory(kvm, range->addr, range->size, &region->npages, 1);
-	if (IS_ERR(region->pages)) {
-		ret = PTR_ERR(region->pages);
-		goto e_free;
-	}
-
-	/*
-	 * The guest may change the memory encryption attribute from C=0 -> C=1
-	 * or vice versa for this memory range. Lets make sure caches are
-	 * flushed to ensure that guest data gets written into memory with
-	 * correct C-bit.
-	 */
-	sev_clflush_pages(region->pages, region->npages);
-
-	region->uaddr = range->addr;
-	region->size = range->size;
-
-	mutex_lock(&kvm->lock);
-	list_add_tail(&region->list, &sev->regions_list);
-	mutex_unlock(&kvm->lock);
-
-	return ret;
-
-e_free:
-	kfree(region);
-	return ret;
-}
-
-static struct enc_region *
-find_enc_region(struct kvm *kvm, struct kvm_enc_region *range)
-{
-	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
-	struct list_head *head = &sev->regions_list;
-	struct enc_region *i;
-
-	list_for_each_entry(i, head, list) {
-		if (i->uaddr == range->addr &&
-		    i->size == range->size)
-			return i;
-	}
-
-	return NULL;
-}
-
-static void __unregister_enc_region_locked(struct kvm *kvm,
-					   struct enc_region *region)
-{
-	sev_unpin_memory(kvm, region->pages, region->npages);
-	list_del(&region->list);
-	kfree(region);
+	return 0;
 }
 
 int svm_unregister_enc_region(struct kvm *kvm,
 			      struct kvm_enc_region *range)
 {
-	struct enc_region *region;
-	int ret;
-
-	mutex_lock(&kvm->lock);
-
-	if (!sev_guest(kvm)) {
-		ret = -ENOTTY;
-		goto failed;
-	}
-
-	region = find_enc_region(kvm, range);
-	if (!region) {
-		ret = -EINVAL;
-		goto failed;
-	}
-
-	/*
-	 * Ensure that all guest tagged cache entries are flushed before
-	 * releasing the pages back to the system for use. CLFLUSH will
-	 * not do this, so issue a WBINVD.
-	 */
-	wbinvd_on_all_cpus();
-
-	__unregister_enc_region_locked(kvm, region);
-
-	mutex_unlock(&kvm->lock);
 	return 0;
-
-failed:
-	mutex_unlock(&kvm->lock);
-	return ret;
 }
 
 void sev_vm_destroy(struct kvm *kvm)
 {
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
-	struct list_head *head = &sev->regions_list;
-	struct list_head *pos, *q;
 	XA_STATE(xas, &sev->pages_xarray, 0);
 	struct page *xa_page;
 
@@ -1196,17 +1092,6 @@ void sev_vm_destroy(struct kvm *kvm)
 	 */
 	wbinvd_on_all_cpus();
 
-	/*
-	 * if userspace was terminated before unregistering the memory regions
-	 * then lets unpin all the registered memory.
-	 */
-	if (!list_empty(head)) {
-		list_for_each_safe(pos, q, head) {
-			__unregister_enc_region_locked(kvm,
-				list_entry(pos, struct enc_region, list));
-		}
-	}
-
 	/* Release each pinned page that SEV tracked in sev->pages_xarray. */
 	xas_for_each(&xas, xa_page, ULONG_MAX) {
 		put_page(xa_page);
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 278c46bc52aa..98d3d7b299cb 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -64,7 +64,6 @@ struct kvm_sev_info {
 	unsigned int handle;	/* SEV firmware handle */
 	int fd;			/* SEV device fd */
 	unsigned long pages_locked; /* Number of pages locked */
-	struct list_head regions_list;  /* List of registered regions */
 	struct xarray pages_xarray; /* List of PFN locked */
 };
 
-- 
2.17.1

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