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Message-ID: <20240215113128.275608-5-nikunj@amd.com>
Date: Thu, 15 Feb 2024 17:01:16 +0530
From: Nikunj A Dadhania <nikunj@....com>
To: <linux-kernel@...r.kernel.org>, <thomas.lendacky@....com>, <bp@...en8.de>,
<x86@...nel.org>, <kvm@...r.kernel.org>
CC: <mingo@...hat.com>, <tglx@...utronix.de>, <dave.hansen@...ux.intel.com>,
<pgonda@...gle.com>, <seanjc@...gle.com>, <pbonzini@...hat.com>,
<nikunj@....com>
Subject: [PATCH v8 04/16] 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. Added define for maximum supported VMPCK.
Also, change function is_vmpck_empty() to snp_is_vmpck_empty() in
preparation for moving to sev.c.
Signed-off-by: Nikunj A Dadhania <nikunj@....com>
Reviewed-by: Tom Lendacky <thomas.lendacky@....com>
Tested-by: Peter Gonda <pgonda@...gle.com>
---
arch/x86/include/asm/sev.h | 1 +
drivers/virt/coco/sev-guest/sev-guest.c | 95 ++++++++++++-------------
2 files changed, 48 insertions(+), 48 deletions(-)
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 0c0b11af9f89..e4f52a606487 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -135,6 +135,7 @@ struct secrets_os_area {
} __packed;
#define VMPCK_KEY_LEN 32
+#define VMPCK_MAX_NUM 4
/* See the SNP spec version 0.9 for secrets page format */
struct snp_secrets_page_layout {
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 596cec03f9eb..646eb215f3c7 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -55,8 +55,7 @@ struct snp_guest_dev {
struct snp_derived_key_req derived_key;
struct snp_ext_report_req ext_report;
} req;
- u32 *os_area_msg_seqno;
- u8 *vmpck;
+ unsigned int vmpck_id;
};
static u32 vmpck_id;
@@ -66,14 +65,22 @@ MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP.
/* Mutex to serialize the shared buffer access and command handling. */
static DEFINE_MUTEX(snp_cmd_mutex);
-static bool is_vmpck_empty(struct snp_guest_dev *snp_dev)
+static inline u8 *snp_get_vmpck(struct snp_guest_dev *snp_dev)
{
- char zero_key[VMPCK_KEY_LEN] = {0};
+ return snp_dev->layout->vmpck0 + snp_dev->vmpck_id * VMPCK_KEY_LEN;
+}
- if (snp_dev->vmpck)
- return !memcmp(snp_dev->vmpck, zero_key, 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;
+}
- return true;
+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);
+
+ return !memcmp(key, zero_key, VMPCK_KEY_LEN);
}
/*
@@ -95,20 +102,22 @@ static bool is_vmpck_empty(struct snp_guest_dev *snp_dev)
*/
static void snp_disable_vmpck(struct snp_guest_dev *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;
+ u8 *key = snp_get_vmpck(snp_dev);
+
+ dev_alert(snp_dev->dev, "Disabling vmpck_id %u to prevent IV reuse.\n",
+ 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_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;
}
@@ -136,11 +145,13 @@ 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)
@@ -150,15 +161,22 @@ 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("VM communication key VMPCK%u is null\n", 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("Crypto context initialization failed\n");
kfree(ctx);
return NULL;
@@ -590,7 +608,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
mutex_lock(&snp_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_cmd_mutex);
return -ENOTTY;
@@ -667,32 +685,14 @@ 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)
+static bool snp_assign_vmpck(struct snp_guest_dev *dev, unsigned int vmpck_id)
{
- u8 *key = NULL;
+ if (WARN_ON((vmpck_id + 1) > VMPCK_MAX_NUM))
+ 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;
}
struct snp_msg_report_resp_hdr {
@@ -728,7 +728,7 @@ static int sev_report_new(struct tsm_report *report, void *data)
guard(mutex)(&snp_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");
return -ENOTTY;
}
@@ -848,21 +848,20 @@ 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) {
- dev_err(dev, "invalid vmpck id %d\n", vmpck_id);
+ snp_dev->layout = layout;
+ if (!snp_assign_vmpck(snp_dev, vmpck_id)) {
+ dev_err(dev, "invalid vmpck id %u\n", vmpck_id);
goto e_unmap;
}
/* Verify that VMPCK is not zero. */
- if (is_vmpck_empty(snp_dev)) {
- dev_err(dev, "vmpck id %d is null\n", vmpck_id);
+ if (snp_is_vmpck_empty(snp_dev)) {
+ dev_err(dev, "vmpck id %u is null\n", vmpck_id);
goto e_unmap;
}
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));
@@ -878,7 +877,7 @@ 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;
@@ -903,7 +902,7 @@ static int __init sev_guest_probe(struct platform_device *pdev)
if (ret)
goto e_free_ctx;
- dev_info(dev, "Initialized SEV guest driver (using vmpck_id %d)\n", vmpck_id);
+ dev_info(dev, "Initialized SEV guest driver (using vmpck_id %u)\n", vmpck_id);
return 0;
e_free_ctx:
--
2.34.1
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