Re: [PATCH v4 5/6] crypto: ccp: Use firmware_upload API for SNP firmware

From: Tom Lendacky
Date: Tue Nov 05 2024 - 17:47:51 EST

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In reply to: Dionna Glaze: "[PATCH v4 5/6] crypto: ccp: Use firmware_upload API for SNP firmware"
Next in thread: Dionna Glaze: "[PATCH v4 6/6] KVM: SVM: Delay legacy platform initialization on SNP"
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On 11/4/24 19:05, Dionna Glaze wrote:
> On init, the ccp device will make /sys/class/firmware/amd/loading etc
> firmware upload API attributes available to late-load a SEV-SNP firmware
> binary.
>
> The firmware upload api errors reported are actionable in the following
> ways:
> * FW_UPLOAD_ERR_HW_ERROR: the machine is in an unstable state and must
> be reset.
> * FW_UPLOAD_ERR_RW_ERROR: the firmware update went bad but can be
> recovered by hotloading the previous firmware version.
> Also used in the case that the kernel used the API wrong (bug).
> * FW_UPLOAD_ERR_FW_INVALID: user error with the data provided, but no
> instability is expected and no recovery actions are needed.
> * FW_UPLOAD_ERR_BUSY: upload attempted at a bad time either due to
> overload or the machine is in the wrong platform state.
>
> synthetic_restore_required:
> Instead of tracking the status of whether an individual GCTX is safe for
> use in a firmware command, force all following commands to fail with an
> error that is indicative of needing a firmware rollback.
>
> To test:
> 1. Build the kernel enabling SEV-SNP as normal and add CONFIG_FW_UPLOAD=y.
> 2. Add the following to your kernel_cmdline: ccp.psp_init_on_probe=0.
> 3.Get an AMD SEV-SNP firmware sbin appropriate to your Epyc chip model at
> https://www.amd.com/en/developer/sev.html and extract to get a .sbin
> file.
> 4. Run the following with your sbinfile in FW:
>
> echo 1 > /sys/class/firmware/snp_dlfw_ex/loading
> cat "${FW?}" > /sys/class/firmware/snp_dlfw_ex/data
> echo 0 > /sys/class/firmware/snp_dlfw_ex/loading
>
> 5. Verify the firmware update message in dmesg.
>
> Co-developed-by: Ashish Kalra <ashish.kalra@xxxxxxx>
> Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
> Tested-by: Ashish Kalra <ashish.kalra@xxxxxxx>
> Signed-off-by: Dionna Glaze <dionnaglaze@xxxxxxxxxx>
> ---
> drivers/crypto/ccp/Kconfig | 2 +
> drivers/crypto/ccp/sev-dev.c | 12 +-
> drivers/crypto/ccp/sev-dev.h | 16 +++
> drivers/crypto/ccp/sev-fw.c | 213 +++++++++++++++++++++++++++++++++++
> 4 files changed, 241 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/crypto/ccp/Kconfig b/drivers/crypto/ccp/Kconfig
> index f394e45e11ab4..520b1c84d11f4 100644
> --- a/drivers/crypto/ccp/Kconfig
> +++ b/drivers/crypto/ccp/Kconfig
> @@ -39,6 +39,8 @@ config CRYPTO_DEV_SP_PSP
> bool "Platform Security Processor (PSP) device"
> default y
> depends on CRYPTO_DEV_CCP_DD && X86_64 && AMD_IOMMU
> + select FW_LOADER
> + select FW_UPLOAD
> help
> Provide support for the AMD Platform Security Processor (PSP).
> The PSP is a dedicated processor that provides support for key
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 32f7b6147905e..8c73f023b6420 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -485,7 +485,7 @@ void snp_free_firmware_page(void *addr)
> }
> EXPORT_SYMBOL_GPL(snp_free_firmware_page);
>
> -static void *sev_fw_alloc(unsigned long len)
> +void *sev_fw_alloc(unsigned long len)
> {
> struct page *page;
>
> @@ -853,6 +853,10 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
> if (WARN_ON_ONCE(!data != !buf_len))
> return -EINVAL;
>
> + ret = sev_snp_synthetic_error(sev, psp_ret);

A comment similar to what you have in the commit log would be nice above
this call.

> + if (ret)
> + return ret;
> +
> /*
> * Copy the incoming data to driver's scratch buffer as __pa() will not
> * work for some memory, e.g. vmalloc'd addresses, and @data may not be
> @@ -1523,7 +1527,7 @@ void *psp_copy_user_blob(u64 uaddr, u32 len)
> }
> EXPORT_SYMBOL_GPL(psp_copy_user_blob);
>
> -static int sev_get_api_version(void)
> +int sev_get_api_version(void)
> {
> struct sev_device *sev = psp_master->sev_data;
> struct sev_user_data_status status;
> @@ -2320,6 +2324,8 @@ int sev_dev_init(struct psp_device *psp)
> if (ret)
> goto e_irq;
>
> + sev_snp_dev_init_firmware_upload(sev);
> +
> dev_notice(dev, "sev enabled\n");
>
> return 0;
> @@ -2398,6 +2404,8 @@ void sev_dev_destroy(struct psp_device *psp)
> kref_put(&misc_dev->refcount, sev_exit);
>
> psp_clear_sev_irq_handler(psp);
> +
> + sev_snp_dev_init_firmware_upload(sev);

Shouldn't this be the destroy call?

> }
>
> static int snp_shutdown_on_panic(struct notifier_block *nb,
> diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h
> index 28add34484ed1..52a423e7df84f 100644
> --- a/drivers/crypto/ccp/sev-dev.h
> +++ b/drivers/crypto/ccp/sev-dev.h
> @@ -59,7 +59,13 @@ struct sev_device {
> bool snp_initialized;
>
> #ifdef CONFIG_FW_UPLOAD
> + /* Lock to protect fw_cancel */
> + struct mutex fw_lock;
> + struct fw_upload *fwl;
> + bool fw_cancel;
> +
> u32 last_snp_asid;
> + bool synthetic_restore_required;
> u64 *snp_asid_to_gctx_pages_map;
> u64 *snp_unbound_gctx_pages;
> u32 snp_unbound_gctx_end;
> @@ -72,12 +78,22 @@ void sev_dev_destroy(struct psp_device *psp);
> void sev_pci_init(void);
> void sev_pci_exit(void);
>
> +void *sev_fw_alloc(unsigned long len);
> +int sev_get_api_version(void);
> +int sev_snp_download_firmware_ex(struct sev_device *sev, const u8 *data, u32 size, int *error);
> +
> #ifdef CONFIG_FW_UPLOAD
> void snp_cmd_bookkeeping_locked(int cmd, struct sev_device *sev, void *data);
> int sev_snp_platform_init_firmware_upload(struct sev_device *sev);
> +void sev_snp_dev_init_firmware_upload(struct sev_device *sev);
> +void sev_snp_destroy_firmware_upload(struct sev_device *sev);
> +int sev_snp_synthetic_error(struct sev_device *sev, int *psp_ret);
> #else
> static inline void snp_cmd_bookkeeping_locked(int cmd, struct sev_device *sev, void *data) { }
> static inline int sev_snp_platform_init_firmware_upload(struct sev_device *sev) { return 0; }
> +static inline void sev_snp_dev_init_firmware_upload(struct sev_device *sev) { }
> +static inline void sev_snp_destroy_firmware_upload(struct sev_device *sev) { }
> +static inline int sev_snp_synthetic_error(struct sev_device *sev, int *psp_ret) { return 0; }
> #endif /* CONFIG_FW_UPLOAD */
>
> #endif /* __SEV_DEV_H */
> diff --git a/drivers/crypto/ccp/sev-fw.c b/drivers/crypto/ccp/sev-fw.c
> index 55a5a572da8f1..97ce90f2af29a 100644
> --- a/drivers/crypto/ccp/sev-fw.c
> +++ b/drivers/crypto/ccp/sev-fw.c
> @@ -4,6 +4,7 @@
> */
>
> #include <linux/firmware.h>
> +#include <linux/psp.h>
> #include <linux/psp-sev.h>
>
> #include <asm/sev.h>
> @@ -115,3 +116,215 @@ int sev_snp_platform_init_firmware_upload(struct sev_device *sev)
> }
> return 0;
> }
> +
> +static enum fw_upload_err snp_dlfw_ex_prepare(struct fw_upload *fw_upload,
> + const u8 *data, u32 size)
> +{
> + return FW_UPLOAD_ERR_NONE;
> +}
> +
> +static enum fw_upload_err snp_dlfw_ex_poll_complete(struct fw_upload *fw_upload)
> +{
> + return FW_UPLOAD_ERR_NONE;
> +}
> +
> +/*
> + * This may be called asynchronously with an on-going update. All other
> + * functions are called sequentially in a single thread. To avoid contention on
> + * register accesses, only update the cancel_request flag. Other functions will
> + * check this flag and handle the cancel request synchronously.
> + */
> +static void snp_dlfw_ex_cancel(struct fw_upload *fw_upload)
> +{
> + struct sev_device *sev = fw_upload->dd_handle;
> +
> + mutex_lock(&sev->fw_lock);
> + sev->fw_cancel = true;
> + mutex_unlock(&sev->fw_lock);

Does this really need a lock? Also, I don't see it being set to false
ever, so the first time an update is canceled it can never be updated again.

> +}
> +
> +static enum fw_upload_err snp_dlfw_ex_err_translate(struct sev_device *sev, int psp_ret)
> +{
> + dev_dbg(sev->dev, "Failed to update SEV firmware: %#x\n", psp_ret);

Blank line.

> + /*
> + * Operation error:
> + * HW_ERROR: Critical error. Machine needs repairs now.
> + * RW_ERROR: Severe error. Roll back to the prior version to recover.
> + * User error:
> + * FW_INVALID: Bad input for this interface.
> + * BUSY: Wrong machine state to run download_firmware_ex.
> + */
> + switch (psp_ret) {
> + case SEV_RET_RESTORE_REQUIRED:
> + dev_warn(sev->dev, "Firmware updated but unusable\n");
> + dev_warn(sev->dev, "Need to do manual firmware rollback!!!\n");

Please keep to a single message so that other messages don't get in
between when outputted.

> + return FW_UPLOAD_ERR_RW_ERROR;
> + case SEV_RET_SHUTDOWN_REQUIRED:
> + /* No state changes made. Not a hardware error. */
> + dev_warn(sev->dev, "Firmware image cannot be live updated\n");
> + return FW_UPLOAD_ERR_FW_INVALID;
> + case SEV_RET_BAD_VERSION:
> + /* No state changes made. Not a hardware error. */
> + dev_warn(sev->dev, "Firmware image is not well formed\n");
> + return FW_UPLOAD_ERR_FW_INVALID;
> + /* SEV-specific errors that can still happen. */
> + case SEV_RET_BAD_SIGNATURE:
> + /* No state changes made. Not a hardware error. */
> + dev_warn(sev->dev, "Firmware image signature is bad\n");
> + return FW_UPLOAD_ERR_FW_INVALID;
> + case SEV_RET_INVALID_PLATFORM_STATE:
> + /* Calling at the wrong time. Not a hardware error. */
> + dev_warn(sev->dev, "Firmware not updated as SEV in INIT state\n");
> + return FW_UPLOAD_ERR_BUSY;
> + case SEV_RET_HWSEV_RET_UNSAFE:
> + dev_err(sev->dev, "Firmware is unstable. Reset your machine!!!\n");
> + return FW_UPLOAD_ERR_HW_ERROR;
> + /* Kernel bug cases. */
> + case SEV_RET_INVALID_PARAM:
> + dev_err(sev->dev, "Download-firmware-EX invalid parameter\n");
> + return FW_UPLOAD_ERR_RW_ERROR;
> + case SEV_RET_INVALID_ADDRESS:
> + dev_err(sev->dev, "Download-firmware-EX invalid address\n");
> + return FW_UPLOAD_ERR_RW_ERROR;
> + default:
> + dev_err(sev->dev, "Unhandled download_firmware_ex err %d\n", psp_ret);
> + return FW_UPLOAD_ERR_HW_ERROR;
> + }
> +}
> +
> +static enum fw_upload_err snp_update_guest_statuses(struct sev_device *sev)

snp_update_guest_contexts

> +{
> + struct sev_data_snp_guest_status status_data;
> + void *snp_guest_status;
> + enum fw_upload_err ret;
> + int error;
> +
> + /*
> + * Force an update of guest context pages after SEV firmware
> + * live update by issuing SNP_GUEST_STATUS on all guest
> + * context pages.
> + */
> + snp_guest_status = sev_fw_alloc(PAGE_SIZE);
> + if (!snp_guest_status)
> + return FW_UPLOAD_ERR_INVALID_SIZE;
> +
> + /*
> + * After the last bound asid-to-gctx page is snp_unbound_gctx_end-many
> + * unbound gctx pages that also need updating.
> + */
> + for (int i = 1; i <= sev->last_snp_asid + sev->snp_unbound_gctx_end; i++) {
> + if (sev->snp_asid_to_gctx_pages_map[i]) {

Let reduce some indentation and do

if (!sev->snp_asid_to_gctx_pages_map[i])
continue;

> + status_data.gctx_paddr = sev->snp_asid_to_gctx_pages_map[i];
> + status_data.address = __psp_pa(snp_guest_status);
> + ret = sev_do_cmd(SEV_CMD_SNP_GUEST_STATUS, &status_data, &error);

... and
if (!ret)
continue;

> + if (ret) {
> + /*
> + * Handle race with SNP VM being destroyed/decommissoned,
> + * if guest context page invalid error is returned,
> + * assume guest has been destroyed.
> + */
> + if (error == SEV_RET_INVALID_GUEST)
> + continue;

Add a blank line here.

And add a comment here about synthetic_restore_required being set.

> + sev->synthetic_restore_required = true;
> + dev_err(sev->dev, "SNP GCTX update error: %#x\n", error);
> + dev_err(sev->dev, "Roll back SNP firmware!\n");

Single message, something like:

"SNP guest context update error %#x, recommend SNP firmware roll back."

> + snp_free_firmware_page(snp_guest_status);

This is done in the goto below, so must be removed.

> + ret = FW_UPLOAD_ERR_RW_ERROR;
> + goto fw_err;
> + }
> + }
> + }
> +fw_err:
> + snp_free_firmware_page(snp_guest_status);
> + return ret;
> +}
> +
> +static enum fw_upload_err snp_dlfw_ex_write(struct fw_upload *fwl, const u8 *data,
> + u32 offset, u32 size, u32 *written)
> +{
> + struct sev_device *sev = fwl->dd_handle;
> + u8 api_major, api_minor, build;
> + int ret, error;
> + bool cancel;
> +
> + if (!sev)
> + return FW_UPLOAD_ERR_HW_ERROR;
> +
> + mutex_lock(&sev->fw_lock);
> + cancel = sev->fw_cancel;
> + mutex_unlock(&sev->fw_lock);

Same question on the mutex, I don't see how this helps with any timing.

> +
> + if (cancel)
> + return FW_UPLOAD_ERR_CANCELED;
> +
> + /*
> + * SEV firmware update is a one-shot update operation, the write()
> + * callback to be invoked multiple times for the same update is
> + * unexpected.
> + */
> + if (offset)
> + return FW_UPLOAD_ERR_INVALID_SIZE;
> +
> + if (sev_get_api_version())
> + return FW_UPLOAD_ERR_HW_ERROR;
> +
> + api_major = sev->api_major;
> + api_minor = sev->api_minor;
> + build = sev->build;
> +
> + ret = sev_snp_download_firmware_ex(sev, data, size, &error);
> + if (ret)
> + return snp_dlfw_ex_err_translate(sev, error);
> +
> + ret = snp_update_guest_statuses(sev);
> + if (ret)
> + return ret;
> +
> + sev_get_api_version();
> + if (api_major != sev->api_major || api_minor != sev->api_minor ||
> + build != sev->build) {
> + dev_info(sev->dev, "SEV firmware updated from %d.%d.%d to %d.%d.%d\n",
> + api_major, api_minor, build,
> + sev->api_major, sev->api_minor, sev->build);
> + } else {
> + dev_info(sev->dev, "SEV firmware same as old %d.%d.%d\n",
> + api_major, api_minor, build);

Maybe something like:
"SEV firmware not updated, same as current version %d.%d.%d"

> + }
> +
> + *written = size;

Blank line.

> + return FW_UPLOAD_ERR_NONE;
> +}
> +
> +static const struct fw_upload_ops snp_dlfw_ex_ops = {
> + .prepare = snp_dlfw_ex_prepare,
> + .write = snp_dlfw_ex_write,
> + .poll_complete = snp_dlfw_ex_poll_complete,
> + .cancel = snp_dlfw_ex_cancel,
> +};
> +
> +void sev_snp_dev_init_firmware_upload(struct sev_device *sev)

snp_init_firmware_upload

> +{
> + struct fw_upload *fwl;
> +
> + fwl = firmware_upload_register(THIS_MODULE, sev->dev, "snp_dlfw_ex", &snp_dlfw_ex_ops, sev);
> +

Remove blank line.

> + if (IS_ERR(fwl))
> + dev_err(sev->dev, "SEV firmware upload initialization error %ld\n", PTR_ERR(fwl));
> +
> + sev->fwl = fwl;
> + mutex_init(&sev->fw_lock);

Probably can't happen, but shouldn't the mutex be initialized before
calling firmware_upload_register()?

> +}
> +
> +void sev_snp_destroy_firmware_upload(struct sev_device *sev)

snp_destroy_firmware_upload

> +{
> + firmware_upload_unregister(sev->fwl);

Should this check that the sev->fwl is valid before trying to call
firmware_upload_unregister()?

> +}
> +
> +int sev_snp_synthetic_error(struct sev_device *sev, int *psp_ret)
> +{
> + if (sev->synthetic_restore_required) {
> + *psp_ret = SEV_RET_RESTORE_REQUIRED;
> + return -EIO;
> + }

Blank line.

Thanks,
Tom

> + return 0;
> +}

Next message: Mark Pearson: "Re: [PATCH v4 00/20] Add support for binding ACPI platform profile to multiple drivers"
Previous message: Hillf Danton: "Re: [syzbot] [block?] [trace?] possible deadlock in blk_trace_ioctl"
In reply to: Dionna Glaze: "[PATCH v4 5/6] crypto: ccp: Use firmware_upload API for SNP firmware"
Next in thread: Dionna Glaze: "[PATCH v4 6/6] KVM: SVM: Delay legacy platform initialization on SNP"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]