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Message-ID: <20230722111909.15166-6-nikunj@amd.com>
Date: Sat, 22 Jul 2023 16:49:00 +0530
From: Nikunj A Dadhania <nikunj@....com>
To: <linux-kernel@...r.kernel.org>, <x86@...nel.org>
CC: <bp@...en8.de>, <thomas.lendacky@....com>,
<dionnaglaze@...gle.com>, <pgonda@...gle.com>, <seanjc@...gle.com>,
<pbonzini@...hat.com>, <nikunj@....com>
Subject: [PATCH v3 05/14] virt: sev-guest: Add vmpck_id to snp_guest_dev struct
Drop vmpck and os_area_msg_seqno pointers so that secret page layout
does not need to be exposed to the sev-guest driver after the rework.
Instead, add helper APIs to access vmpck and os_area_msg_seqno when
needed.
Signed-off-by: Nikunj A Dadhania <nikunj@....com>
---
drivers/virt/coco/sev-guest/sev-guest.c | 84 +++++++++++++------------
1 file changed, 43 insertions(+), 41 deletions(-)
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index d4241048b397..8ad43e007d3b 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -50,8 +50,7 @@ struct snp_guest_dev {
struct snp_secrets_page_layout *layout;
struct snp_req_data input;
- u32 *os_area_msg_seqno;
- u8 *vmpck;
+ unsigned int vmpck_id;
};
static u32 vmpck_id;
@@ -67,12 +66,23 @@ static inline unsigned int get_ctx_authsize(struct snp_guest_dev *snp_dev)
return 0;
}
-static bool is_vmpck_empty(struct snp_guest_dev *snp_dev)
+static inline u8 *snp_get_vmpck(struct snp_guest_dev *snp_dev)
+{
+ return snp_dev->layout->vmpck0 + snp_dev->vmpck_id * VMPCK_KEY_LEN;
+}
+
+static inline u32 *snp_get_os_area_msg_seqno(struct snp_guest_dev *snp_dev)
+{
+ return &snp_dev->layout->os_area.msg_seqno_0 + snp_dev->vmpck_id;
+}
+
+static bool snp_is_vmpck_empty(struct snp_guest_dev *snp_dev)
{
char zero_key[VMPCK_KEY_LEN] = {0};
+ u8 *key = snp_get_vmpck(snp_dev);
- if (snp_dev->vmpck)
- return !memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN);
+ if (key)
+ return !memcmp(key, zero_key, VMPCK_KEY_LEN);
return true;
}
@@ -96,20 +106,22 @@ static bool is_vmpck_empty(struct snp_guest_dev *snp_dev)
*/
static void snp_disable_vmpck(struct snp_guest_dev *snp_dev)
{
+ u8 *key = snp_get_vmpck(snp_dev);
+
dev_alert(snp_dev->dev, "Disabling vmpck_id %d to prevent IV reuse.\n",
- vmpck_id);
- memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN);
- snp_dev->vmpck = NULL;
+ snp_dev->vmpck_id);
+ memzero_explicit(key, VMPCK_KEY_LEN);
}
static inline u64 __snp_get_msg_seqno(struct snp_guest_dev *snp_dev)
{
+ u32 *os_area_msg_seqno = snp_get_os_area_msg_seqno(snp_dev);
u64 count;
lockdep_assert_held(&snp_dev->cmd_mutex);
/* Read the current message sequence counter from secrets pages */
- count = *snp_dev->os_area_msg_seqno;
+ count = *os_area_msg_seqno;
return count + 1;
}
@@ -137,11 +149,13 @@ static u64 snp_get_msg_seqno(struct snp_guest_dev *snp_dev)
static void snp_inc_msg_seqno(struct snp_guest_dev *snp_dev)
{
+ u32 *os_area_msg_seqno = snp_get_os_area_msg_seqno(snp_dev);
+
/*
* The counter is also incremented by the PSP, so increment it by 2
* and save in secrets page.
*/
- *snp_dev->os_area_msg_seqno += 2;
+ *os_area_msg_seqno += 2;
}
static inline struct snp_guest_dev *to_snp_dev(struct file *file)
@@ -151,15 +165,22 @@ static inline struct snp_guest_dev *to_snp_dev(struct file *file)
return container_of(dev, struct snp_guest_dev, misc);
}
-static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen)
+static struct aesgcm_ctx *snp_init_crypto(struct snp_guest_dev *snp_dev)
{
struct aesgcm_ctx *ctx;
+ u8 *key;
+
+ if (snp_is_vmpck_empty(snp_dev)) {
+ pr_err("SNP: vmpck id %d is null\n", snp_dev->vmpck_id);
+ return NULL;
+ }
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT);
if (!ctx)
return NULL;
- if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) {
+ key = snp_get_vmpck(snp_dev);
+ if (aesgcm_expandkey(ctx, key, VMPCK_KEY_LEN, AUTHTAG_LEN)) {
pr_err("SNP: crypto init failed\n");
kfree(ctx);
return NULL;
@@ -606,7 +627,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
mutex_lock(&snp_dev->cmd_mutex);
/* Check if the VMPCK is not empty */
- if (is_vmpck_empty(snp_dev)) {
+ if (snp_is_vmpck_empty(snp_dev)) {
dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n");
mutex_unlock(&snp_dev->cmd_mutex);
return -ENOTTY;
@@ -676,32 +697,14 @@ static const struct file_operations snp_guest_fops = {
.unlocked_ioctl = snp_guest_ioctl,
};
-static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno)
+bool snp_assign_vmpck(struct snp_guest_dev *dev, int vmpck_id)
{
- u8 *key = NULL;
+ if (WARN_ON(vmpck_id > 3))
+ return false;
- switch (id) {
- case 0:
- *seqno = &layout->os_area.msg_seqno_0;
- key = layout->vmpck0;
- break;
- case 1:
- *seqno = &layout->os_area.msg_seqno_1;
- key = layout->vmpck1;
- break;
- case 2:
- *seqno = &layout->os_area.msg_seqno_2;
- key = layout->vmpck2;
- break;
- case 3:
- *seqno = &layout->os_area.msg_seqno_3;
- key = layout->vmpck3;
- break;
- default:
- break;
- }
+ dev->vmpck_id = vmpck_id;
- return key;
+ return true;
}
static int __init sev_guest_probe(struct platform_device *pdev)
@@ -733,14 +736,14 @@ static int __init sev_guest_probe(struct platform_device *pdev)
goto e_unmap;
ret = -EINVAL;
- snp_dev->vmpck = get_vmpck(vmpck_id, layout, &snp_dev->os_area_msg_seqno);
- if (!snp_dev->vmpck) {
+ snp_dev->layout = layout;
+ if (!snp_assign_vmpck(snp_dev, vmpck_id)) {
dev_err(dev, "invalid vmpck id %d\n", vmpck_id);
goto e_unmap;
}
/* Verify that VMPCK is not zero. */
- if (is_vmpck_empty(snp_dev)) {
+ if (snp_is_vmpck_empty(snp_dev)) {
dev_err(dev, "vmpck id %d is null\n", vmpck_id);
goto e_unmap;
}
@@ -748,7 +751,6 @@ static int __init sev_guest_probe(struct platform_device *pdev)
mutex_init(&snp_dev->cmd_mutex);
platform_set_drvdata(pdev, snp_dev);
snp_dev->dev = dev;
- snp_dev->layout = layout;
/* Allocate the shared page used for the request and response message. */
snp_dev->request = alloc_shared_pages(dev, sizeof(struct snp_guest_msg));
@@ -764,7 +766,7 @@ static int __init sev_guest_probe(struct platform_device *pdev)
goto e_free_response;
ret = -EIO;
- snp_dev->ctx = snp_init_crypto(snp_dev->vmpck, VMPCK_KEY_LEN);
+ snp_dev->ctx = snp_init_crypto(snp_dev);
if (!snp_dev->ctx)
goto e_free_cert_data;
--
2.34.1
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