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Sampat wrote: >> In preparation for refreshing the cached SNP platform status and feature >> information after a successful firmware live update from >> DOWNLOAD_FIRMWARE_EX, allow snp_get_platform_data() to be called while >> the SNP firmware is in the INIT state. >> >> Once SNP is initialized the firmware requires the output page of both >> commands to be firmware-owned. sev->snp_plat_status cannot satisfy that >> as it is embedded in struct sev_device, so use >> __sev_do_snp_platform_status(), which stages the output through a >> dedicated page. Allocate the SNP_FEATURE_INFO output page with >> __snp_alloc_firmware_pages(), which transitions the page to >> firmware-owned when SNP is initialized, and release it with >> __snp_free_firmware_pages(), which reclaims it before freeing. >> >> Typically this was only ever exercised during initialization. However >> DOWNLOAD_FIRMWARE_EX can change that. Live firmware update can race with >> IOCTLs such as SEV_FACTORY_RESET which could cause operations performed >> on incorrect cached platform states. Avoid this race by wrapping the >> function under the sev_cmd_mutex. >> >> Co-developed-by: Tycho Andersen (AMD) >> Signed-off-by: Tycho Andersen (AMD) >> Signed-off-by: Pratik R. Sampat > > Just a minor comment below. > > Reviewed-by: Tom Lendacky > >> --- >> drivers/crypto/ccp/sev-dev.c | 27 ++++++++++++--------------- >> 1 file changed, 12 insertions(+), 15 deletions(-) >> >> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c >> index 1ed9e61a95cc..c40401c861d3 100644 >> --- a/drivers/crypto/ccp/sev-dev.c >> +++ b/drivers/crypto/ccp/sev-dev.c >> @@ -131,6 +131,8 @@ static void __sev_firmware_shutdown(struct sev_device *sev, bool panic); >> >> static int snp_shutdown_on_panic(struct notifier_block *nb, >> unsigned long reason, void *arg); >> +static int __sev_do_snp_platform_status(struct sev_user_data_snp_status *status, >> + int *error); >> >> static struct notifier_block snp_panic_notifier = { >> .notifier_call = snp_shutdown_on_panic, >> @@ -1261,19 +1263,12 @@ static int snp_get_platform_data(struct sev_device *sev, int *error) >> { >> struct sev_data_snp_feature_info snp_feat_info; >> struct snp_feature_info *feat_info; >> - struct sev_data_snp_addr buf; >> struct page *page; >> int rc; >> >> - /* >> - * This function is expected to be called before SNP is >> - * initialized. >> - */ >> - if (sev->snp_initialized) >> - return -EINVAL; >> + lockdep_assert_held(&sev_cmd_mutex); >> >> - buf.address = __psp_pa(&sev->snp_plat_status); >> - rc = sev_do_cmd(SEV_CMD_SNP_PLATFORM_STATUS, &buf, error); >> + rc = __sev_do_snp_platform_status(&sev->snp_plat_status, error); >> if (rc) { >> dev_err(sev->dev, "SNP PLATFORM_STATUS command failed, ret = %d, error = %#x\n", >> rc, *error); >> @@ -1297,23 +1292,23 @@ static int snp_get_platform_data(struct sev_device *sev, int *error) >> * command to ensure structure is 8-byte aligned, and does not >> * cross a page boundary. >> */ >> - page = alloc_page(GFP_KERNEL); >> - if (!page) >> + page = __snp_alloc_firmware_pages(GFP_KERNEL, 0, true); >> + feat_info = page ? page_address(page) : NULL; >> + if (!feat_info) >> return -ENOMEM; >> >> - feat_info = page_address(page); > > This is a bit of churn when all you have to do is replace alloc_page() > with __snp_alloc_firmware_pages(), right? > I'll clean that right up! Thanks, --Pratik > Thanks, > Tom > >> snp_feat_info.length = sizeof(snp_feat_info); >> snp_feat_info.ecx_in = 0; >> snp_feat_info.feature_info_paddr = __psp_pa(feat_info); >> >> - rc = sev_do_cmd(SEV_CMD_SNP_FEATURE_INFO, &snp_feat_info, error); >> + rc = __sev_do_cmd_locked(SEV_CMD_SNP_FEATURE_INFO, &snp_feat_info, error); >> if (!rc) >> sev->snp_feat_info_0 = *feat_info; >> else >> dev_err(sev->dev, "SNP FEATURE_INFO command failed, ret = %d, error = %#x\n", >> rc, *error); >> >> - __free_page(page); >> + __snp_free_firmware_pages(page, 0, true); >> >> return rc; >> } >> @@ -2097,6 +2092,8 @@ static int sev_get_api_version(void) >> struct sev_user_data_status status; >> int error = 0, ret; >> >> + guard(mutex)(&sev_cmd_mutex); >> + >> /* >> * Cache SNP platform status and SNP feature information >> * if SNP is available. >> @@ -2107,7 +2104,7 @@ static int sev_get_api_version(void) >> return 1; >> } >> >> - ret = sev_platform_status(&status, &error); >> + ret = __sev_do_cmd_locked(SEV_CMD_PLATFORM_STATUS, &status, &error); >> if (ret) { >> dev_err(sev->dev, >> "SEV: failed to get status. Error: %#x\n", error); >