[PATCH v1 2/4] KVM: PPC: Book3S HV: track shared GFNs of secure VMs
Ram Pai
linuxram at us.ibm.com
Sun May 31 12:27:49 AEST 2020
During the life of SVM, its GFNs can transition from secure to shared
state and vice-versa. Since the kernel does not track GFNs that are
shared, it is not possible to disambiguate a shared GFN from a GFN whose
PFN has not yet been migrated to a device-PFN.
The ability to identify a shared GFN is needed to skip migrating its PFN
to device PFN. This functionality is leveraged in a subsequent patch.
Add the ability to identify the state of a GFN.
Cc: Paul Mackerras <paulus at ozlabs.org>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Bharata B Rao <bharata at linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
Cc: Laurent Dufour <ldufour at linux.ibm.com>
Cc: Thiago Jung Bauermann <bauerman at linux.ibm.com>
Cc: David Gibson <david at gibson.dropbear.id.au>
Cc: Claudio Carvalho <cclaudio at linux.ibm.com>
Cc: kvm-ppc at vger.kernel.org
Cc: linuxppc-dev at lists.ozlabs.org
Reviewed-by: Thiago Jung Bauermann <bauerman at linux.ibm.com>
Signed-off-by: Ram Pai <linuxram at us.ibm.com>
---
arch/powerpc/include/asm/kvm_book3s_uvmem.h | 6 +-
arch/powerpc/kvm/book3s_64_mmu_radix.c | 2 +-
arch/powerpc/kvm/book3s_hv.c | 2 +-
arch/powerpc/kvm/book3s_hv_uvmem.c | 115 ++++++++++++++++++++++++++--
4 files changed, 113 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_book3s_uvmem.h b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
index 5a9834e..f0c5708 100644
--- a/arch/powerpc/include/asm/kvm_book3s_uvmem.h
+++ b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
@@ -21,7 +21,8 @@ unsigned long kvmppc_h_svm_page_out(struct kvm *kvm,
int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn);
unsigned long kvmppc_h_svm_init_abort(struct kvm *kvm);
void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
- struct kvm *kvm, bool skip_page_out);
+ struct kvm *kvm, bool skip_page_out,
+ bool purge_gfn);
#else
static inline int kvmppc_uvmem_init(void)
{
@@ -75,6 +76,7 @@ static inline int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn)
static inline void
kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
- struct kvm *kvm, bool skip_page_out) { }
+ struct kvm *kvm, bool skip_page_out,
+ bool purge_gfn) { }
#endif /* CONFIG_PPC_UV */
#endif /* __ASM_KVM_BOOK3S_UVMEM_H__ */
diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index 803940d..3448459 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -1100,7 +1100,7 @@ void kvmppc_radix_flush_memslot(struct kvm *kvm,
unsigned int shift;
if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START)
- kvmppc_uvmem_drop_pages(memslot, kvm, true);
+ kvmppc_uvmem_drop_pages(memslot, kvm, true, false);
if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE)
return;
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 103d13e..4c62bfe 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -5467,7 +5467,7 @@ static int kvmhv_svm_off(struct kvm *kvm)
continue;
kvm_for_each_memslot(memslot, slots) {
- kvmppc_uvmem_drop_pages(memslot, kvm, true);
+ kvmppc_uvmem_drop_pages(memslot, kvm, true, true);
uv_unregister_mem_slot(kvm->arch.lpid, memslot->id);
}
}
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index ea4a1f1..2ef1e03 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -99,14 +99,56 @@
static DEFINE_SPINLOCK(kvmppc_uvmem_bitmap_lock);
#define KVMPPC_UVMEM_PFN (1UL << 63)
+#define KVMPPC_UVMEM_SHARED (1UL << 62)
+#define KVMPPC_UVMEM_FLAG_MASK (KVMPPC_UVMEM_PFN | KVMPPC_UVMEM_SHARED)
+#define KVMPPC_UVMEM_PFN_MASK (~KVMPPC_UVMEM_FLAG_MASK)
struct kvmppc_uvmem_slot {
struct list_head list;
unsigned long nr_pfns;
unsigned long base_pfn;
+ /*
+ * pfns array has an entry for each GFN of the memory slot.
+ *
+ * The GFN can be in one of the following states.
+ *
+ * (a) Secure - The GFN is secure. Only Ultravisor can access it.
+ * (b) Shared - The GFN is shared. Both Hypervisor and Ultravisor
+ * can access it.
+ * (c) Normal - The GFN is a normal. Only Hypervisor can access it.
+ *
+ * Secure GFN is associated with a devicePFN. Its pfn[] has
+ * KVMPPC_UVMEM_PFN flag set, and has the value of the device PFN
+ * KVMPPC_UVMEM_SHARED flag unset, and has the value of the device PFN
+ *
+ * Shared GFN is associated with a memoryPFN. Its pfn[] has
+ * KVMPPC_UVMEM_SHARED flag set. But its KVMPPC_UVMEM_PFN is not set,
+ * and there is no PFN value stored.
+ *
+ * Normal GFN is not associated with memoryPFN. Its pfn[] has
+ * KVMPPC_UVMEM_SHARED and KVMPPC_UVMEM_PFN flag unset, and no PFN
+ * value is stored.
+ *
+ * Any other combination of values in pfn[] leads to undefined
+ * behavior.
+ *
+ * Life cycle of a GFN --
+ *
+ * ---------------------------------------------------------
+ * | | Share | Unshare | SVM |slot |
+ * | | | | abort/ |flush |
+ * | | | | terminate | |
+ * ---------------------------------------------------------
+ * | | | | | |
+ * | Secure | Shared | Secure |Normal |Secure |
+ * | | | | | |
+ * | Shared | Shared | Secure |Normal |Shared |
+ * | | | | | |
+ * | Normal | Shared | Secure |Normal |Normal |
+ * ---------------------------------------------------------
+ */
unsigned long *pfns;
};
-
struct kvmppc_uvmem_page_pvt {
struct kvm *kvm;
unsigned long gpa;
@@ -175,7 +217,12 @@ static void kvmppc_uvmem_pfn_remove(unsigned long gfn, struct kvm *kvm)
list_for_each_entry(p, &kvm->arch.uvmem_pfns, list) {
if (gfn >= p->base_pfn && gfn < p->base_pfn + p->nr_pfns) {
- p->pfns[gfn - p->base_pfn] = 0;
+ /*
+ * Reset everything, but keep the KVMPPC_UVMEM_SHARED
+ * flag intact. A gfn continues to be shared or
+ * unshared, with or without an associated device pfn.
+ */
+ p->pfns[gfn - p->base_pfn] &= KVMPPC_UVMEM_SHARED;
return;
}
}
@@ -193,7 +240,7 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm,
if (p->pfns[index] & KVMPPC_UVMEM_PFN) {
if (uvmem_pfn)
*uvmem_pfn = p->pfns[index] &
- ~KVMPPC_UVMEM_PFN;
+ KVMPPC_UVMEM_PFN_MASK;
return true;
} else
return false;
@@ -202,6 +249,38 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm,
return false;
}
+static void kvmppc_gfn_uvmem_shared(unsigned long gfn, struct kvm *kvm,
+ bool set)
+{
+ struct kvmppc_uvmem_slot *p;
+
+ list_for_each_entry(p, &kvm->arch.uvmem_pfns, list) {
+ if (gfn >= p->base_pfn && gfn < p->base_pfn + p->nr_pfns) {
+ unsigned long index = gfn - p->base_pfn;
+
+ if (set)
+ p->pfns[index] |= KVMPPC_UVMEM_SHARED;
+ else
+ p->pfns[index] &= ~KVMPPC_UVMEM_SHARED;
+ return;
+ }
+ }
+}
+
+bool kvmppc_gfn_is_uvmem_shared(unsigned long gfn, struct kvm *kvm)
+{
+ struct kvmppc_uvmem_slot *p;
+
+ list_for_each_entry(p, &kvm->arch.uvmem_pfns, list) {
+ if (gfn >= p->base_pfn && gfn < p->base_pfn + p->nr_pfns) {
+ unsigned long index = gfn - p->base_pfn;
+
+ return (p->pfns[index] & KVMPPC_UVMEM_SHARED);
+ }
+ }
+ return false;
+}
+
unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
{
struct kvm_memslots *slots;
@@ -256,9 +335,13 @@ unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)
* is HV side fault on these pages. Next we *get* these pages, forcing
* fault on them, do fault time migration to replace the device PTEs in
* QEMU page table with normal PTEs from newly allocated pages.
+ *
+ * if @purge_gfn is set, cleanup any information related to each of
+ * the GFNs associated with this memory slot.
*/
void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
- struct kvm *kvm, bool skip_page_out)
+ struct kvm *kvm, bool skip_page_out,
+ bool purge_gfn)
{
int i;
struct kvmppc_uvmem_page_pvt *pvt;
@@ -269,11 +352,22 @@ void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
struct page *uvmem_page;
mutex_lock(&kvm->arch.uvmem_lock);
+
+ if (purge_gfn) {
+ /*
+ * cleanup the shared status of the GFN here.
+ * Any device PFN associated with the GFN shall
+ * be cleaned up later, in kvmppc_uvmem_page_free()
+ * when the device PFN is actually disassociated
+ * from the GFN.
+ */
+ kvmppc_gfn_uvmem_shared(gfn, kvm, false);
+ }
+
if (!kvmppc_gfn_is_uvmem_pfn(gfn, kvm, &uvmem_pfn)) {
mutex_unlock(&kvm->arch.uvmem_lock);
continue;
}
-
uvmem_page = pfn_to_page(uvmem_pfn);
pvt = uvmem_page->zone_device_data;
pvt->skip_page_out = skip_page_out;
@@ -304,7 +398,7 @@ unsigned long kvmppc_h_svm_init_abort(struct kvm *kvm)
srcu_idx = srcu_read_lock(&kvm->srcu);
kvm_for_each_memslot(memslot, kvm_memslots(kvm))
- kvmppc_uvmem_drop_pages(memslot, kvm, false);
+ kvmppc_uvmem_drop_pages(memslot, kvm, false, true);
srcu_read_unlock(&kvm->srcu, srcu_idx);
@@ -470,8 +564,11 @@ static unsigned long kvmppc_share_page(struct kvm *kvm, unsigned long gpa,
goto retry;
}
- if (!uv_page_in(kvm->arch.lpid, pfn << page_shift, gpa, 0, page_shift))
+ if (!uv_page_in(kvm->arch.lpid, pfn << page_shift, gpa, 0,
+ page_shift)) {
+ kvmppc_gfn_uvmem_shared(gfn, kvm, true);
ret = H_SUCCESS;
+ }
kvm_release_pfn_clean(pfn);
mutex_unlock(&kvm->arch.uvmem_lock);
out:
@@ -527,8 +624,10 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa,
goto out_unlock;
if (!kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift,
- &downgrade))
+ &downgrade)) {
+ kvmppc_gfn_uvmem_shared(gfn, kvm, false);
ret = H_SUCCESS;
+ }
out_unlock:
mutex_unlock(&kvm->arch.uvmem_lock);
out:
--
1.8.3.1
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