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

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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: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Tianyu Lan <tiala@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20230818102919.1318039-5-ltykernel@gmail.com
This commit is contained in:
Tianyu Lan 2023-08-18 06:29:14 -04:00 committed by Wei Liu
parent b13103559d
commit 193061ea0a
2 changed files with 67 additions and 3 deletions
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57
drivers/hv/hv.c
View File

@ -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);
}

13
drivers/hv/hv_common.c
View File

@ -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);