From 8ef979584ea86c247b768f4420148721a842835f Mon Sep 17 00:00:00 2001 From: Ashish Kalra Date: Thu, 25 Jan 2024 22:11:20 -0600 Subject: [PATCH] crypto: ccp: Add panic notifier for SEV/SNP firmware shutdown on kdump Add a kdump safe version of sev_firmware_shutdown() and register it as a crash_kexec_post_notifier so it will be invoked during panic/crash to do SEV/SNP shutdown. This is required for transitioning all IOMMU pages to reclaim/hypervisor state, otherwise re-init of IOMMU pages during crashdump kernel boot fails and panics the crashdump kernel. This panic notifier runs in atomic context, hence it ensures not to acquire any locks/mutexes and polls for PSP command completion instead of depending on PSP command completion interrupt. [ mdr: Remove use of "we" in comments. ] Signed-off-by: Ashish Kalra Signed-off-by: Michael Roth Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240126041126.1927228-21-michael.roth@amd.com --- arch/x86/include/asm/sev.h | 2 + arch/x86/kernel/crash.c | 3 + arch/x86/kernel/sev.c | 10 ++++ arch/x86/virt/svm/sev.c | 6 ++ drivers/crypto/ccp/sev-dev.c | 111 +++++++++++++++++++++++++---------- 5 files changed, 102 insertions(+), 30 deletions(-) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 60de1b43a729..bed95e1f4d52 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -227,6 +227,7 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn void snp_accept_memory(phys_addr_t start, phys_addr_t end); u64 snp_get_unsupported_features(u64 status); u64 sev_get_status(void); +void kdump_sev_callback(void); #else static inline void sev_es_ist_enter(struct pt_regs *regs) { } static inline void sev_es_ist_exit(void) { } @@ -255,6 +256,7 @@ static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *in static inline void snp_accept_memory(phys_addr_t start, phys_addr_t end) { } static inline u64 snp_get_unsupported_features(u64 status) { return 0; } static inline u64 sev_get_status(void) { return 0; } +static inline void kdump_sev_callback(void) { } #endif #ifdef CONFIG_KVM_AMD_SEV diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index b6b044356f1b..d184c29398db 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -40,6 +40,7 @@ #include #include #include +#include /* Used while preparing memory map entries for second kernel */ struct crash_memmap_data { @@ -59,6 +60,8 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs) */ cpu_emergency_stop_pt(); + kdump_sev_callback(); + disable_local_APIC(); } diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 1ec753331524..002af6c30601 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -2265,3 +2265,13 @@ static int __init snp_init_platform_device(void) return 0; } device_initcall(snp_init_platform_device); + +void kdump_sev_callback(void) +{ + /* + * Do wbinvd() on remote CPUs when SNP is enabled in order to + * safely do SNP_SHUTDOWN on the local CPU. + */ + if (cpu_feature_enabled(X86_FEATURE_SEV_SNP)) + wbinvd(); +} diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c index 0dffbf3908d0..cffe1157a90a 100644 --- a/arch/x86/virt/svm/sev.c +++ b/arch/x86/virt/svm/sev.c @@ -216,6 +216,12 @@ skip_enable: cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/rmptable_init:online", __snp_enable, NULL); + /* + * Setting crash_kexec_post_notifiers to 'true' to ensure that SNP panic + * notifier is invoked to do SNP IOMMU shutdown before kdump. + */ + crash_kexec_post_notifiers = true; + return 0; nosnp: diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 605c6bf88cf7..504a2216bded 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include @@ -143,6 +144,25 @@ static int sev_wait_cmd_ioc(struct sev_device *sev, { int ret; + /* + * If invoked during panic handling, local interrupts are disabled, + * so the PSP command completion interrupt can't be used. Poll for + * PSP command completion instead. + */ + if (irqs_disabled()) { + unsigned long timeout_usecs = (timeout * USEC_PER_SEC) / 10; + + /* Poll for SEV command completion: */ + while (timeout_usecs--) { + *reg = ioread32(sev->io_regs + sev->vdata->cmdresp_reg); + if (*reg & PSP_CMDRESP_RESP) + return 0; + + udelay(10); + } + return -ETIMEDOUT; + } + ret = wait_event_timeout(sev->int_queue, sev->int_rcvd, timeout * HZ); if (!ret) @@ -1338,17 +1358,6 @@ static int __sev_platform_shutdown_locked(int *error) return ret; } -static int sev_platform_shutdown(int *error) -{ - int rc; - - mutex_lock(&sev_cmd_mutex); - rc = __sev_platform_shutdown_locked(NULL); - mutex_unlock(&sev_cmd_mutex); - - return rc; -} - static int sev_get_platform_state(int *state, int *error) { struct sev_user_data_status data; @@ -1624,7 +1633,7 @@ fw_err: return ret; } -static int __sev_snp_shutdown_locked(int *error) +static int __sev_snp_shutdown_locked(int *error, bool panic) { struct sev_device *sev = psp_master->sev_data; struct sev_data_snp_shutdown_ex data; @@ -1637,7 +1646,16 @@ static int __sev_snp_shutdown_locked(int *error) data.len = sizeof(data); data.iommu_snp_shutdown = 1; - wbinvd_on_all_cpus(); + /* + * If invoked during panic handling, local interrupts are disabled + * and all CPUs are stopped, so wbinvd_on_all_cpus() can't be called. + * In that case, a wbinvd() is done on remote CPUs via the NMI + * callback, so only a local wbinvd() is needed here. + */ + if (!panic) + wbinvd_on_all_cpus(); + else + wbinvd(); ret = __sev_do_cmd_locked(SEV_CMD_SNP_SHUTDOWN_EX, &data, error); /* SHUTDOWN may require DF_FLUSH */ @@ -1681,17 +1699,6 @@ static int __sev_snp_shutdown_locked(int *error) return ret; } -static int sev_snp_shutdown(int *error) -{ - int rc; - - mutex_lock(&sev_cmd_mutex); - rc = __sev_snp_shutdown_locked(error); - mutex_unlock(&sev_cmd_mutex); - - return rc; -} - static int sev_ioctl_do_pek_import(struct sev_issue_cmd *argp, bool writable) { struct sev_device *sev = psp_master->sev_data; @@ -2139,19 +2146,28 @@ e_err: return ret; } -static void sev_firmware_shutdown(struct sev_device *sev) +static void __sev_firmware_shutdown(struct sev_device *sev, bool panic) { int error; - sev_platform_shutdown(NULL); + __sev_platform_shutdown_locked(NULL); if (sev_es_tmr) { - /* The TMR area was encrypted, flush it from the cache */ - wbinvd_on_all_cpus(); + /* + * The TMR area was encrypted, flush it from the cache. + * + * If invoked during panic handling, local interrupts are + * disabled and all CPUs are stopped, so wbinvd_on_all_cpus() + * can't be used. In that case, wbinvd() is done on remote CPUs + * via the NMI callback, and done for this CPU later during + * SNP shutdown, so wbinvd_on_all_cpus() can be skipped. + */ + if (!panic) + wbinvd_on_all_cpus(); __snp_free_firmware_pages(virt_to_page(sev_es_tmr), get_order(sev_es_tmr_size), - false); + true); sev_es_tmr = NULL; } @@ -2167,7 +2183,14 @@ static void sev_firmware_shutdown(struct sev_device *sev) snp_range_list = NULL; } - sev_snp_shutdown(&error); + __sev_snp_shutdown_locked(&error, panic); +} + +static void sev_firmware_shutdown(struct sev_device *sev) +{ + mutex_lock(&sev_cmd_mutex); + __sev_firmware_shutdown(sev, false); + mutex_unlock(&sev_cmd_mutex); } void sev_dev_destroy(struct psp_device *psp) @@ -2185,6 +2208,29 @@ void sev_dev_destroy(struct psp_device *psp) psp_clear_sev_irq_handler(psp); } +static int snp_shutdown_on_panic(struct notifier_block *nb, + unsigned long reason, void *arg) +{ + struct sev_device *sev = psp_master->sev_data; + + /* + * If sev_cmd_mutex is already acquired, then it's likely + * another PSP command is in flight and issuing a shutdown + * would fail in unexpected ways. Rather than create even + * more confusion during a panic, just bail out here. + */ + if (mutex_is_locked(&sev_cmd_mutex)) + return NOTIFY_DONE; + + __sev_firmware_shutdown(sev, true); + + return NOTIFY_DONE; +} + +static struct notifier_block snp_panic_notifier = { + .notifier_call = snp_shutdown_on_panic, +}; + int sev_issue_cmd_external_user(struct file *filep, unsigned int cmd, void *data, int *error) { @@ -2222,6 +2268,8 @@ void sev_pci_init(void) dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_initialized ? "-SNP" : "", sev->api_major, sev->api_minor, sev->build); + atomic_notifier_chain_register(&panic_notifier_list, + &snp_panic_notifier); return; err: @@ -2236,4 +2284,7 @@ void sev_pci_exit(void) return; sev_firmware_shutdown(sev); + + atomic_notifier_chain_unregister(&panic_notifier_list, + &snp_panic_notifier); }