Commit 193061ea authored by Tianyu Lan's avatar Tianyu Lan Committed by Wei Liu
Browse files

drivers: hv: Mark percpu hvcall input arg page unencrypted in SEV-SNP enlightened guest 



Hypervisor needs to access input arg, VMBus synic event and
message pages. Mark these pages unencrypted in the SEV-SNP
guest and free them only if they have been marked encrypted
successfully.

Reviewed-by: default avatarDexuan Cui <decui@microsoft.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarTianyu Lan <tiala@microsoft.com>
Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20230818102919.1318039-5-ltykernel@gmail.com
parent b1310355

drivers/hv/hv.c

+54 −3
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/interrupt.h>

#include <clocksource/hyperv_timer.h>

#include <asm/mshyperv.h>

#include <linux/set_memory.h>

#include "hyperv_vmbus.h"



/* The one and only */
@@ -78,7 +79,7 @@ int hv_post_message(union hv_connection_id connection_id, 


int hv_synic_alloc(void)

{

	int cpu;

	int cpu, ret = -ENOMEM;

	struct hv_per_cpu_context *hv_cpu;



	/*
@@ -123,26 +124,76 @@ int hv_synic_alloc(void) 
				goto err;

			}

		}



		if (hv_isolation_type_en_snp()) {

			ret = set_memory_decrypted((unsigned long)

				hv_cpu->synic_message_page, 1);

			if (ret) {

				pr_err("Failed to decrypt SYNIC msg page: %d\n", ret);

				hv_cpu->synic_message_page = NULL;



				/*

				 * Free the event page here so that hv_synic_free()

				 * won't later try to re-encrypt it.

				 */

				free_page((unsigned long)hv_cpu->synic_event_page);

				hv_cpu->synic_event_page = NULL;

				goto err;

			}



			ret = set_memory_decrypted((unsigned long)

				hv_cpu->synic_event_page, 1);

			if (ret) {

				pr_err("Failed to decrypt SYNIC event page: %d\n", ret);

				hv_cpu->synic_event_page = NULL;

				goto err;

			}



			memset(hv_cpu->synic_message_page, 0, PAGE_SIZE);

			memset(hv_cpu->synic_event_page, 0, PAGE_SIZE);

		}

	}



	return 0;



err:

	/*

	 * Any memory allocations that succeeded will be freed when

	 * the caller cleans up by calling hv_synic_free()

	 */

	return -ENOMEM;

	return ret;

}





void hv_synic_free(void)

{

	int cpu;

	int cpu, ret;



	for_each_present_cpu(cpu) {

		struct hv_per_cpu_context *hv_cpu

			= per_cpu_ptr(hv_context.cpu_context, cpu);



		/* It's better to leak the page if the encryption fails. */

		if (hv_isolation_type_en_snp()) {

			if (hv_cpu->synic_message_page) {

				ret = set_memory_encrypted((unsigned long)

					hv_cpu->synic_message_page, 1);

				if (ret) {

					pr_err("Failed to encrypt SYNIC msg page: %d\n", ret);

					hv_cpu->synic_message_page = NULL;

				}

			}



			if (hv_cpu->synic_event_page) {

				ret = set_memory_encrypted((unsigned long)

					hv_cpu->synic_event_page, 1);

				if (ret) {

					pr_err("Failed to encrypt SYNIC event page: %d\n", ret);

					hv_cpu->synic_event_page = NULL;

				}

			}

		}



		free_page((unsigned long)hv_cpu->synic_event_page);

		free_page((unsigned long)hv_cpu->synic_message_page);

	}

drivers/hv/hv_common.c

+13 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <linux/kmsg_dump.h>

#include <linux/slab.h>

#include <linux/dma-map-ops.h>

#include <linux/set_memory.h>

#include <asm/hyperv-tlfs.h>

#include <asm/mshyperv.h>
@@ -359,6 +360,7 @@ int hv_common_cpu_init(unsigned int cpu) 
	u64 msr_vp_index;

	gfp_t flags;

	int pgcount = hv_root_partition ? 2 : 1;

	int ret;



	/* hv_cpu_init() can be called with IRQs disabled from hv_resume() */

	flags = irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL;
@@ -378,6 +380,17 @@ int hv_common_cpu_init(unsigned int cpu) 
			outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);

			*outputarg = (char *)(*inputarg) + HV_HYP_PAGE_SIZE;

		}



		if (hv_isolation_type_en_snp()) {

			ret = set_memory_decrypted((unsigned long)*inputarg, pgcount);

			if (ret) {

				kfree(*inputarg);

				*inputarg = NULL;

				return ret;

			}



			memset(*inputarg, 0x00, pgcount * PAGE_SIZE);

		}

	}



	msr_vp_index = hv_get_register(HV_REGISTER_VP_INDEX);