hv_netvsc: Remove second mapping of send and recv buffers

With changes to how Hyper-V guest VMs flip memory between private
(encrypted) and shared (decrypted), creating a second kernel virtual
mapping for shared memory is no longer necessary. Everything needed
for the transition to shared is handled by set_memory_decrypted().

As such, remove the code to create and manage the second
mapping for the pre-allocated send and recv buffers. This mapping
is the last user of hv_map_memory()/hv_unmap_memory(), so delete
these functions as well. Finally, hv_map_memory() is the last
user of vmap_pfn() in Hyper-V guest code, so remove the Kconfig
selection of VMAP_PFN.

Signed-off-by: Michael Kelley <[e-mail]>
Reviewed-by: Tianyu Lan <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Wei Liu <[e-mail]>

arch/x86/hyperv/ivm.c

···
 
 #endif /* CONFIG_AMD_MEM_ENCRYPT */
 
-/*
- * hv_map_memory - map memory to extra space in the AMD SEV-SNP Isolation VM.
- */
-void *hv_map_memory(void *addr, unsigned long size)
-{
-	unsigned long *pfns = kcalloc(size / PAGE_SIZE,
-				      sizeof(unsigned long), GFP_KERNEL);
-	void *vaddr;
-	int i;
-
-	if (!pfns)
-		return NULL;
-
-	for (i = 0; i < size / PAGE_SIZE; i++)
-		pfns[i] = vmalloc_to_pfn(addr + i * PAGE_SIZE) +
-			(ms_hyperv.shared_gpa_boundary >> PAGE_SHIFT);
-
-	vaddr = vmap_pfn(pfns, size / PAGE_SIZE, pgprot_decrypted(PAGE_KERNEL));
-	kfree(pfns);
-
-	return vaddr;
-}
-
-void hv_unmap_memory(void *addr)
-{
-	vunmap(addr);
-}
-
 enum hv_isolation_type hv_get_isolation_type(void)
 {
 	if (!(ms_hyperv.priv_high & HV_ISOLATION))

drivers/hv/Kconfig

···
 		|| (ACPI && ARM64 && !CPU_BIG_ENDIAN)
 	select PARAVIRT
 	select X86_HV_CALLBACK_VECTOR if X86
-	select VMAP_PFN
 	select OF_EARLY_FLATTREE if OF
 	help
 	  Select this option to run Linux as a Hyper-V client operating

drivers/hv/hv_common.c

···
 	return HV_STATUS_INVALID_PARAMETER;
 }
 EXPORT_SYMBOL_GPL(hv_ghcb_hypercall);
-
-void __weak *hv_map_memory(void *addr, unsigned long size)
-{
-	return NULL;
-}
-EXPORT_SYMBOL_GPL(hv_map_memory);
-
-void __weak hv_unmap_memory(void *addr)
-{
-}
-EXPORT_SYMBOL_GPL(hv_unmap_memory);

drivers/net/hyperv/hyperv_net.h

···
 
 	/* Receive buffer allocated by us but manages by NetVSP */
 	void *recv_buf;
-	void *recv_original_buf;
 	u32 recv_buf_size; /* allocated bytes */
 	struct vmbus_gpadl recv_buf_gpadl_handle;
 	u32 recv_section_cnt;
···
 
 	/* Send buffer allocated by us */
 	void *send_buf;
-	void *send_original_buf;
 	u32 send_buf_size;
 	struct vmbus_gpadl send_buf_gpadl_handle;
 	u32 send_section_cnt;

drivers/net/hyperv/netvsc.c

···
 	int i;
 
 	kfree(nvdev->extension);
-
-	if (nvdev->recv_original_buf)
-		vfree(nvdev->recv_original_buf);
-	else
-		vfree(nvdev->recv_buf);
-
-	if (nvdev->send_original_buf)
-		vfree(nvdev->send_original_buf);
-	else
-		vfree(nvdev->send_buf);
-
+	vfree(nvdev->recv_buf);
+	vfree(nvdev->send_buf);
 	bitmap_free(nvdev->send_section_map);
 
 	for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
···
 	struct nvsp_message *init_packet;
 	unsigned int buf_size;
 	int i, ret = 0;
-	void *vaddr;
 
 	/* Get receive buffer area. */
 	buf_size = device_info->recv_sections * device_info->recv_section_size;
···
 		netdev_err(ndev,
 			"unable to establish receive buffer's gpadl\n");
 		goto cleanup;
-	}
-
-	if (hv_isolation_type_snp()) {
-		vaddr = hv_map_memory(net_device->recv_buf, buf_size);
-		if (!vaddr) {
-			ret = -ENOMEM;
-			goto cleanup;
-		}
-
-		net_device->recv_original_buf = net_device->recv_buf;
-		net_device->recv_buf = vaddr;
 	}
 
 	/* Notify the NetVsp of the gpadl handle */
···
 		netdev_err(ndev,
 			   "unable to establish send buffer's gpadl\n");
 		goto cleanup;
-	}
-
-	if (hv_isolation_type_snp()) {
-		vaddr = hv_map_memory(net_device->send_buf, buf_size);
-		if (!vaddr) {
-			ret = -ENOMEM;
-			goto cleanup;
-		}
-
-		net_device->send_original_buf = net_device->send_buf;
-		net_device->send_buf = vaddr;
 	}
 
 	/* Notify the NetVsp of the gpadl handle */
···
 		netvsc_teardown_recv_gpadl(device, net_device, ndev);
 		netvsc_teardown_send_gpadl(device, net_device, ndev);
 	}
-
-	if (net_device->recv_original_buf)
-		hv_unmap_memory(net_device->recv_buf);
-
-	if (net_device->send_original_buf)
-		hv_unmap_memory(net_device->send_buf);
 
 	/* Release all resources */
 	free_netvsc_device_rcu(net_device);
···
 	netif_napi_del(&net_device->chan_table[0].napi);
 
 cleanup2:
-	if (net_device->recv_original_buf)
-		hv_unmap_memory(net_device->recv_buf);
-
-	if (net_device->send_original_buf)
-		hv_unmap_memory(net_device->send_buf);
-
 	free_netvsc_device(&net_device->rcu);
 
 	return ERR_PTR(ret);

include/asm-generic/mshyperv.h

···
 void hyperv_cleanup(void);
 bool hv_query_ext_cap(u64 cap_query);
 void hv_setup_dma_ops(struct device *dev, bool coherent);
-void *hv_map_memory(void *addr, unsigned long size);
-void hv_unmap_memory(void *addr);
 #else /* CONFIG_HYPERV */
 static inline bool hv_is_hyperv_initialized(void) { return false; }
 static inline bool hv_is_hibernation_supported(void) { return false; }