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Date: Thu, 1 Jun 2023 11:16:17 -0400
From: Tianyu Lan <ltykernel@...il.com>
To: kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
decui@...rosoft.com, tglx@...utronix.de, mingo@...hat.com,
bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
hpa@...or.com, daniel.lezcano@...aro.org, arnd@...db.de,
michael.h.kelley@...rosoft.com
Cc: Tianyu Lan <tiala@...rosoft.com>, linux-arch@...r.kernel.org,
linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
vkuznets@...hat.com
Subject: [PATCH 4/9] drivers: hv: Mark shared pages unencrypted in SEV-SNP enlightened guest
From: Tianyu Lan <tiala@...rosoft.com>
Hypervisor needs to access iput arg, VMBus synic event and
message pages. Mask these pages unencrypted in the sev-snp
guest and free them only if they have been marked encrypted
successfully.
Signed-off-by: Tianyu Lan <tiala@...rosoft.com>
---
drivers/hv/hv.c | 57 +++++++++++++++++++++++++++++++++++++++---
drivers/hv/hv_common.c | 24 +++++++++++++++++-
2 files changed, 77 insertions(+), 4 deletions(-)
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index de6708dbe0df..94406dbe0df0 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -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 and not encrypt
+ * the page in hv_synic_free().
+ */
+ 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);
}
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 179bc5f5bf52..bed9aa6ac19a 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -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;
@@ -368,6 +370,17 @@ int hv_common_cpu_init(unsigned int cpu)
if (!(*inputarg))
return -ENOMEM;
+ 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);
+ }
+
if (hv_root_partition) {
outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
*outputarg = (char *)(*inputarg) + HV_HYP_PAGE_SIZE;
@@ -387,7 +400,9 @@ int hv_common_cpu_die(unsigned int cpu)
{
unsigned long flags;
void **inputarg, **outputarg;
+ int pgcount = hv_root_partition ? 2 : 1;
void *mem;
+ int ret;
local_irq_save(flags);
@@ -402,7 +417,14 @@ int hv_common_cpu_die(unsigned int cpu)
local_irq_restore(flags);
- kfree(mem);
+ if (hv_isolation_type_en_snp()) {
+ ret = set_memory_encrypted((unsigned long)mem, pgcount);
+ if (ret)
+ pr_warn("Hyper-V: Failed to encrypt input arg on cpu%d: %d\n",
+ cpu, ret);
+ /* It's unsafe to free 'mem'. */
+ return 0;
+ }
return 0;
}
--
2.25.1
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