FROMLIST: gunyah: rsc_mgr: Add platform ops on mem_lend/mem_reclaim

On Qualcomm platforms, there is a firmware entity which controls access
to physical pages. In order to share memory with another VM, this entity
needs to be informed that the guest VM should have access to the memory.

Bug: 338347082
Link: https://lore.kernel.org/all/20240222-gunyah-v17-21-1e9da6763d38@quicinc.com/
Change-Id: If56960856b5e4f3ca906a6171d0f50aea978c57e
Co-developed-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Signed-off-by: Elliot Berman <elliot.berman@oss.qualcomm.com>

drivers/virt/gunyah/Kconfig

@@ -3,6 +3,7 @@
 config GUNYAH
 	tristate "Gunyah Virtualization drivers"
 	depends on ARM64
+	select GUNYAH_PLATFORM_HOOKS
 	help
 	  The Gunyah drivers are the helper interfaces that run in a guest VM
 	  such as basic inter-VM IPC and signaling mechanisms, and higher level
@@ -10,3 +11,6 @@ config GUNYAH
 
 	  Say Y/M here to enable the drivers needed to interact in a Gunyah
 	  virtual environment.
+
+config GUNYAH_PLATFORM_HOOKS
+	tristate

drivers/virt/gunyah/Makefile

@@ -3,3 +3,4 @@
 gunyah_rsc_mgr-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o vm_mgr_mem.o
 
 obj-$(CONFIG_GUNYAH) += gunyah.o gunyah_rsc_mgr.o gunyah_vcpu.o
+obj-$(CONFIG_GUNYAH_PLATFORM_HOOKS) += gunyah_platform_hooks.o

drivers/virt/gunyah/gunyah_platform_hooks.c

@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022-2024 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/device.h>
+#include <linux/gunyah.h>
+#include <linux/module.h>
+#include <linux/rwsem.h>
+
+#include "rsc_mgr.h"
+
+static const struct gunyah_rm_platform_ops *rm_platform_ops;
+static DECLARE_RWSEM(rm_platform_ops_lock);
+
+int gunyah_rm_platform_pre_mem_share(struct gunyah_rm *rm,
+				     struct gunyah_rm_mem_parcel *mem_parcel)
+{
+	int ret = 0;
+
+	down_read(&rm_platform_ops_lock);
+	if (rm_platform_ops && rm_platform_ops->pre_mem_share)
+		ret = rm_platform_ops->pre_mem_share(rm, mem_parcel);
+	up_read(&rm_platform_ops_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gunyah_rm_platform_pre_mem_share);
+
+int gunyah_rm_platform_post_mem_reclaim(struct gunyah_rm *rm,
+					struct gunyah_rm_mem_parcel *mem_parcel)
+{
+	int ret = 0;
+
+	down_read(&rm_platform_ops_lock);
+	if (rm_platform_ops && rm_platform_ops->post_mem_reclaim)
+		ret = rm_platform_ops->post_mem_reclaim(rm, mem_parcel);
+	up_read(&rm_platform_ops_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gunyah_rm_platform_post_mem_reclaim);
+
+int gunyah_rm_platform_pre_demand_page(struct gunyah_rm *rm, u16 vmid,
+				       enum gunyah_pagetable_access access,
+				       struct folio *folio)
+{
+	int ret = 0;
+
+	down_read(&rm_platform_ops_lock);
+	if (rm_platform_ops && rm_platform_ops->pre_demand_page)
+		ret = rm_platform_ops->pre_demand_page(rm, vmid, access, folio);
+	up_read(&rm_platform_ops_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gunyah_rm_platform_pre_demand_page);
+
+int gunyah_rm_platform_reclaim_demand_page(struct gunyah_rm *rm, u16 vmid,
+					   enum gunyah_pagetable_access access,
+					   struct folio *folio)
+{
+	int ret = 0;
+
+	down_read(&rm_platform_ops_lock);
+	if (rm_platform_ops && rm_platform_ops->pre_demand_page)
+		ret = rm_platform_ops->release_demand_page(rm, vmid, access,
+							   folio);
+	up_read(&rm_platform_ops_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gunyah_rm_platform_reclaim_demand_page);
+
+int gunyah_rm_register_platform_ops(
+	const struct gunyah_rm_platform_ops *platform_ops)
+{
+	int ret = 0;
+
+	down_write(&rm_platform_ops_lock);
+	if (!rm_platform_ops)
+		rm_platform_ops = platform_ops;
+	else
+		ret = -EEXIST;
+	up_write(&rm_platform_ops_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gunyah_rm_register_platform_ops);
+
+void gunyah_rm_unregister_platform_ops(
+	const struct gunyah_rm_platform_ops *platform_ops)
+{
+	down_write(&rm_platform_ops_lock);
+	if (rm_platform_ops == platform_ops)
+		rm_platform_ops = NULL;
+	up_write(&rm_platform_ops_lock);
+}
+EXPORT_SYMBOL_GPL(gunyah_rm_unregister_platform_ops);
+
+static void _devm_gunyah_rm_unregister_platform_ops(void *data)
+{
+	gunyah_rm_unregister_platform_ops(
+		(const struct gunyah_rm_platform_ops *)data);
+}
+
+int devm_gunyah_rm_register_platform_ops(
+	struct device *dev, const struct gunyah_rm_platform_ops *ops)
+{
+	int ret;
+
+	ret = gunyah_rm_register_platform_ops(ops);
+	if (ret)
+		return ret;
+
+	return devm_add_action(dev, _devm_gunyah_rm_unregister_platform_ops,
+			       (void *)ops);
+}
+EXPORT_SYMBOL_GPL(devm_gunyah_rm_register_platform_ops);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Gunyah Platform Hooks");

drivers/virt/gunyah/rsc_mgr.h

@@ -117,4 +117,14 @@ int gunyah_rm_call(struct gunyah_rm *rsc_mgr, u32 message_id,
 		   const void *req_buf, size_t req_buf_size, void **resp_buf,
 		   size_t *resp_buf_size);
 
+int gunyah_rm_platform_pre_mem_share(struct gunyah_rm *rm,
+				     struct gunyah_rm_mem_parcel *mem_parcel);
+int gunyah_rm_platform_post_mem_reclaim(
+	struct gunyah_rm *rm, struct gunyah_rm_mem_parcel *mem_parcel);
+
+int gunyah_rm_platform_pre_demand_page(struct gunyah_rm *rm, u16 vmid,
+				       u32 flags, struct folio *folio);
+int gunyah_rm_platform_reclaim_demand_page(struct gunyah_rm *rm, u16 vmid,
+					   u32 flags, struct folio *folio);
+
 #endif

drivers/virt/gunyah/rsc_mgr_rpc.c

@@ -209,6 +209,12 @@ int gunyah_rm_mem_share(struct gunyah_rm *rm, struct gunyah_rm_mem_parcel *p)
 	if (!msg)
 		return -ENOMEM;
 
+	ret = gunyah_rm_platform_pre_mem_share(rm, p);
+	if (ret) {
+		kfree(msg);
+		return ret;
+	}
+
 	req_header = msg;
 	acl = (void *)req_header + sizeof(*req_header);
 	mem = (void *)acl + acl_size;
@@ -234,8 +240,10 @@ int gunyah_rm_mem_share(struct gunyah_rm *rm, struct gunyah_rm_mem_parcel *p)
 			     &resp_size);
 	kfree(msg);
 
-	if (ret)
+	if (ret) {
+		gunyah_rm_platform_post_mem_reclaim(rm, p);
 		return ret;
+	}
 
 	p->mem_handle = le32_to_cpu(*resp);
 	kfree(resp);
@@ -267,9 +275,15 @@ int gunyah_rm_mem_reclaim(struct gunyah_rm *rm,
 	struct gunyah_rm_mem_release_req req = {
 		.mem_handle = cpu_to_le32(parcel->mem_handle),
 	};
+	int ret;
 
-	return gunyah_rm_call(rm, GUNYAH_RM_RPC_MEM_RECLAIM, &req, sizeof(req),
-			      NULL, NULL);
+	ret = gunyah_rm_call(rm, GUNYAH_RM_RPC_MEM_RECLAIM, &req, sizeof(req),
+			     NULL, NULL);
+	/* Only call platform mem reclaim hooks if we reclaimed the memory */
+	if (ret)
+		return ret;
+
+	return gunyah_rm_platform_post_mem_reclaim(rm, parcel);
 }
 ALLOW_ERROR_INJECTION(gunyah_rm_mem_reclaim, ERRNO);
 

drivers/virt/gunyah/vm_mgr_mem.c

@@ -9,6 +9,7 @@
 #include <linux/mm.h>
 #include <linux/pagemap.h>
 
+#include "rsc_mgr.h"
 #include "vm_mgr.h"
 
 #define WRITE_TAG (1 << 0)
@@ -107,7 +108,7 @@ int gunyah_vm_provide_folio(struct gunyah_vm *ghvm, struct folio *folio,
 	size_t size = folio_size(folio);
 	enum gunyah_error gunyah_error;
 	unsigned long tag = 0;
-	int ret;
+	int ret, tmp;
 
 	/* clang-format off */
 	if (share) {
@@ -158,6 +159,11 @@ int gunyah_vm_provide_folio(struct gunyah_vm *ghvm, struct folio *folio,
 	else /* !share && !write */
 		access = GUNYAH_PAGETABLE_ACCESS_RX;
 
+	ret = gunyah_rm_platform_pre_demand_page(ghvm->rm, ghvm->vmid, access,
+						 folio);
+	if (ret)
+		goto reclaim_host;
+
 	gunyah_error = gunyah_hypercall_memextent_donate(donate_flags(share),
 							 host_extent->capid,
 							 guest_extent->capid,
@@ -166,7 +172,7 @@ int gunyah_vm_provide_folio(struct gunyah_vm *ghvm, struct folio *folio,
 		pr_err("Failed to donate memory for guest address 0x%016llx: %d\n",
 		       gpa, gunyah_error);
 		ret = gunyah_error_remap(gunyah_error);
-		goto remove;
+		goto platform_release;
 	}
 
 	extent_attrs =
@@ -197,6 +203,16 @@ memextent_reclaim:
 	if (gunyah_error != GUNYAH_ERROR_OK)
 		pr_err("Failed to reclaim memory donation for guest address 0x%016llx: %d\n",
 		       gpa, gunyah_error);
+platform_release:
+	tmp = gunyah_rm_platform_reclaim_demand_page(ghvm->rm, ghvm->vmid,
+						     access, folio);
+	if (tmp) {
+		pr_err("Platform failed to reclaim memory for guest address 0x%016llx: %d",
+		       gpa, tmp);
+		return ret;
+	}
+reclaim_host:
+	gunyah_folio_host_reclaim(folio);
 remove:
 	mtree_erase(&ghvm->mm, gfn);
 	return ret;
@@ -207,6 +223,7 @@ static int __gunyah_vm_reclaim_folio_locked(struct gunyah_vm *ghvm, void *entry,
 {
 	u32 map_flags = BIT(GUNYAH_ADDRSPACE_MAP_FLAG_PARTIAL);
 	struct gunyah_resource *guest_extent, *host_extent, *addrspace;
+	enum gunyah_pagetable_access access;
 	enum gunyah_error gunyah_error;
 	struct folio *folio;
 	bool write, share;
@@ -264,6 +281,24 @@ static int __gunyah_vm_reclaim_folio_locked(struct gunyah_vm *ghvm, void *entry,
 		goto err;
 	}
 
+	if (share && write)
+		access = GUNYAH_PAGETABLE_ACCESS_RW;
+	else if (share && !write)
+		access = GUNYAH_PAGETABLE_ACCESS_R;
+	else if (!share && write)
+		access = GUNYAH_PAGETABLE_ACCESS_RWX;
+	else /* !share && !write */
+		access = GUNYAH_PAGETABLE_ACCESS_RX;
+
+	ret = gunyah_rm_platform_reclaim_demand_page(ghvm->rm, ghvm->vmid,
+						     access, folio);
+	if (ret) {
+		pr_err_ratelimited(
+			"Platform failed to reclaim memory for guest address 0x%016llx: %d",
+			gunyah_gfn_to_gpa(gfn), ret);
+		goto err;
+	}
+
 	BUG_ON(mtree_erase(&ghvm->mm, gfn) != entry);
 
 	if (folio_test_private(folio)) {

include/linux/gunyah.h

@@ -198,6 +198,57 @@ struct gunyah_rm_mem_parcel {
 	u32 mem_handle;
 };
 
+enum gunyah_pagetable_access {
+	/* clang-format off */
+	GUNYAH_PAGETABLE_ACCESS_NONE		= 0,
+	GUNYAH_PAGETABLE_ACCESS_X		= 1,
+	GUNYAH_PAGETABLE_ACCESS_W		= 2,
+	GUNYAH_PAGETABLE_ACCESS_R		= 4,
+	GUNYAH_PAGETABLE_ACCESS_RX		= 5,
+	GUNYAH_PAGETABLE_ACCESS_RW		= 6,
+	GUNYAH_PAGETABLE_ACCESS_RWX		= 7,
+	/* clang-format on */
+};
+
+struct gunyah_rm_platform_ops {
+	int (*pre_mem_share)(struct gunyah_rm *rm,
+			     struct gunyah_rm_mem_parcel *mem_parcel);
+	int (*post_mem_reclaim)(struct gunyah_rm *rm,
+				struct gunyah_rm_mem_parcel *mem_parcel);
+
+	int (*pre_demand_page)(struct gunyah_rm *rm, u16 vmid,
+			       enum gunyah_pagetable_access access,
+			       struct folio *folio);
+	int (*release_demand_page)(struct gunyah_rm *rm, u16 vmid,
+				   enum gunyah_pagetable_access access,
+				   struct folio *folio);
+};
+
+#if IS_ENABLED(CONFIG_GUNYAH_PLATFORM_HOOKS)
+int gunyah_rm_register_platform_ops(
+	const struct gunyah_rm_platform_ops *platform_ops);
+void gunyah_rm_unregister_platform_ops(
+	const struct gunyah_rm_platform_ops *platform_ops);
+int devm_gunyah_rm_register_platform_ops(
+	struct device *dev, const struct gunyah_rm_platform_ops *ops);
+#else
+static inline int gunyah_rm_register_platform_ops(
+	const struct gunyah_rm_platform_ops *platform_ops)
+{
+	return 0;
+}
+static inline void gunyah_rm_unregister_platform_ops(
+	const struct gunyah_rm_platform_ops *platform_ops)
+{
+}
+static inline int
+devm_gunyah_rm_register_platform_ops(struct device *dev,
+				     const struct gunyah_rm_platform_ops *ops)
+{
+	return 0;
+}
+#endif
+
 /******************************************************************************/
 /* Common arch-independent definitions for Gunyah hypercalls                  */
 #define GUNYAH_CAPID_INVAL U64_MAX
@@ -318,18 +369,6 @@ enum gunyah_error gunyah_hypercall_msgq_recv(u64 capid, void *buff, size_t size,
 
 #define GUNYAH_ADDRSPACE_SELF_CAP 0
 
-enum gunyah_pagetable_access {
-	/* clang-format off */
-	GUNYAH_PAGETABLE_ACCESS_NONE		= 0,
-	GUNYAH_PAGETABLE_ACCESS_X		= 1,
-	GUNYAH_PAGETABLE_ACCESS_W		= 2,
-	GUNYAH_PAGETABLE_ACCESS_R		= 4,
-	GUNYAH_PAGETABLE_ACCESS_RX		= 5,
-	GUNYAH_PAGETABLE_ACCESS_RW		= 6,
-	GUNYAH_PAGETABLE_ACCESS_RWX		= 7,
-	/* clang-format on */
-};
-
 /* clang-format off */
 #define GUNYAH_MEMEXTENT_MAPPING_USER_ACCESS		GENMASK_ULL(2, 0)
 #define GUNYAH_MEMEXTENT_MAPPING_KERNEL_ACCESS		GENMASK_ULL(6, 4)