| Message ID | 20231230161954.569267-22-michael.roth@amd.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Initialization Support | expand |
On Sat, Dec 30, 2023 at 10:19:49AM -0600, Michael Roth wrote: > From: Ashish Kalra <ashish.kalra@amd.com> > > Add a kdump safe version of sev_firmware_shutdown() registered as a > crash_kexec_post_notifier, which is 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. > > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > [mdr: remove use of "we" in comments] > Signed-off-by: Michael Roth <michael.roth@amd.com> Cleanups ontop, see if the below works too. Especially: * I've zapped the WBINVD before the TMR pages are freed because __sev_snp_shutdown_locked() will WBINVD anyway. * The mutex_is_locked() check in snp_shutdown_on_panic() is silly because the panic notifier runs on one CPU anyway. Thx. --- diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 435ba9bc4510..27323203e593 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 23ede774d31b..64ae3a1e5c30 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -40,6 +40,7 @@ #include <asm/intel_pt.h> #include <asm/crash.h> #include <asm/cmdline.h> +#include <asm/sev.h> /* Used while preparing memory map entries for second kernel */ struct crash_memmap_data { @@ -59,12 +60,7 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs) */ cpu_emergency_stop_pt(); - /* - * for SNP do wbinvd() on remote CPUs to - * safely do SNP_SHUTDOWN on the local CPU. - */ - if (cpu_feature_enabled(X86_FEATURE_SEV_SNP)) - wbinvd(); + kdump_sev_callback(); disable_local_APIC(); } diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index c67285824e82..dbb2cc6b5666 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -2262,3 +2262,13 @@ 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 the local CPU. + */ + if (cpu_feature_enabled(X86_FEATURE_SEV_SNP)) + wbinvd(); +} diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 598878e760bc..c342e5e54e45 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -161,7 +161,6 @@ static int sev_wait_cmd_ioc(struct sev_device *sev, udelay(10); } - return -ETIMEDOUT; } @@ -1654,7 +1653,7 @@ static int sev_update_firmware(struct device *dev) return ret; } -static int __sev_snp_shutdown_locked(int *error, bool in_panic) +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; @@ -1673,7 +1672,7 @@ static int __sev_snp_shutdown_locked(int *error, bool in_panic) * In that case, a wbinvd() is done on remote CPUs via the NMI * callback, so only a local wbinvd() is needed here. */ - if (!in_panic) + if (!panic) wbinvd_on_all_cpus(); else wbinvd(); @@ -2199,26 +2198,13 @@ int sev_dev_init(struct psp_device *psp) return ret; } -static void __sev_firmware_shutdown(struct sev_device *sev, bool in_panic) +static void __sev_firmware_shutdown(struct sev_device *sev, bool panic) { int error; __sev_platform_shutdown_locked(NULL); if (sev_es_tmr) { - /* - * 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, so a local wbinvd() is sufficient here. - */ - if (!in_panic) - wbinvd_on_all_cpus(); - else - wbinvd(); - __snp_free_firmware_pages(virt_to_page(sev_es_tmr), get_order(sev_es_tmr_size), true); @@ -2237,7 +2223,7 @@ static void __sev_firmware_shutdown(struct sev_device *sev, bool in_panic) snp_range_list = NULL; } - __sev_snp_shutdown_locked(&error, in_panic); + __sev_snp_shutdown_locked(&error, panic); } static void sev_firmware_shutdown(struct sev_device *sev) @@ -2262,26 +2248,18 @@ void sev_dev_destroy(struct psp_device *psp) psp_clear_sev_irq_handler(psp); } -static int sev_snp_shutdown_on_panic(struct notifier_block *nb, - unsigned long reason, void *arg) +static int snp_shutdown_on_panic(struct notifier_block *nb, + unsigned long reason, void *arg) { struct sev_device *sev = psp_master->sev_data; - /* - * Panic callbacks are executed with all other CPUs stopped, - * so don't wait for sev_cmd_mutex to be released since it - * would block here forever. - */ - if (mutex_is_locked(&sev_cmd_mutex)) - return NOTIFY_DONE; - __sev_firmware_shutdown(sev, true); return NOTIFY_DONE; } -static struct notifier_block sev_snp_panic_notifier = { - .notifier_call = sev_snp_shutdown_on_panic, +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, @@ -2322,7 +2300,7 @@ void sev_pci_init(void) "-SNP" : "", sev->api_major, sev->api_minor, sev->build); atomic_notifier_chain_register(&panic_notifier_list, - &sev_snp_panic_notifier); + &snp_panic_notifier); return; err: @@ -2339,5 +2317,5 @@ void sev_pci_exit(void) sev_firmware_shutdown(sev); atomic_notifier_chain_unregister(&panic_notifier_list, - &sev_snp_panic_notifier); + &snp_panic_notifier); }
Hello Boris, On 1/21/2024 5:49 AM, Borislav Petkov wrote: > On Sat, Dec 30, 2023 at 10:19:49AM -0600, Michael Roth wrote: >> From: Ashish Kalra <ashish.kalra@amd.com> >> >> Add a kdump safe version of sev_firmware_shutdown() registered as a >> crash_kexec_post_notifier, which is 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. >> >> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> >> [mdr: remove use of "we" in comments] >> Signed-off-by: Michael Roth <michael.roth@amd.com> > Cleanups ontop, see if the below works too. Especially: > > * I've zapped the WBINVD before the TMR pages are freed because > __sev_snp_shutdown_locked() will WBINVD anyway. This flush is required for TMR, as TMR is encrypted and it needs to be flushed from cache before being reclaimed and freed, therefore this flush is required. SNP_SHUTDOWN_EX may additionally require wbinvd + DF_FLUSH, therefore there is another WBINVD in __sev_snp_shutdown_locked(). > > * The mutex_is_locked() check in snp_shutdown_on_panic() is silly > because the panic notifier runs on one CPU anyway. But, what if there is an active command on the PSP when panic occurs, the mutex will already be acquired in such a case and we can't issue another PSP command if there is an active PSP command, so i believe this check is required. Thanks, Ashish
On Sun, Jan 21, 2024 at 12:49:00PM +0100, Borislav Petkov wrote: > On Sat, Dec 30, 2023 at 10:19:49AM -0600, Michael Roth wrote: > > From: Ashish Kalra <ashish.kalra@amd.com> > > > > Add a kdump safe version of sev_firmware_shutdown() registered as a > > crash_kexec_post_notifier, which is 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. > > > > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > > [mdr: remove use of "we" in comments] > > Signed-off-by: Michael Roth <michael.roth@amd.com> > > Cleanups ontop, see if the below works too. Especially: > > * I've zapped the WBINVD before the TMR pages are freed because > __sev_snp_shutdown_locked() will WBINVD anyway. As Ashish mentioned the wbinvd_on_all_cpus() is still needed for general TMR handling even outside of panic/SNP, but I think you're right about the panic==true where the handling is SNP-specific and so the wbinvd() that gets called later during SNP shutdown will take care of it, so I've adjusted things accordingly. > > * The mutex_is_locked() check in snp_shutdown_on_panic() is silly > because the panic notifier runs on one CPU anyway. Based on discussion with Ashish I've updated the comments in v2 regarding this to make it a little clearer why it might still be a good idea to keep that in to avoid weird unexpected behavior if we try to issue PSP commands while another one was already in-flight by another task before the panic. But I squashed in all the other changes here as-is. -Mike > > Thx. > > --- > > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index 435ba9bc4510..27323203e593 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 23ede774d31b..64ae3a1e5c30 100644 > --- a/arch/x86/kernel/crash.c > +++ b/arch/x86/kernel/crash.c > @@ -40,6 +40,7 @@ > #include <asm/intel_pt.h> > #include <asm/crash.h> > #include <asm/cmdline.h> > +#include <asm/sev.h> > > /* Used while preparing memory map entries for second kernel */ > struct crash_memmap_data { > @@ -59,12 +60,7 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs) > */ > cpu_emergency_stop_pt(); > > - /* > - * for SNP do wbinvd() on remote CPUs to > - * safely do SNP_SHUTDOWN on the local CPU. > - */ > - if (cpu_feature_enabled(X86_FEATURE_SEV_SNP)) > - wbinvd(); > + kdump_sev_callback(); > > disable_local_APIC(); > } > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index c67285824e82..dbb2cc6b5666 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -2262,3 +2262,13 @@ 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 the local CPU. > + */ > + if (cpu_feature_enabled(X86_FEATURE_SEV_SNP)) > + wbinvd(); > +} > diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c > index 598878e760bc..c342e5e54e45 100644 > --- a/drivers/crypto/ccp/sev-dev.c > +++ b/drivers/crypto/ccp/sev-dev.c > @@ -161,7 +161,6 @@ static int sev_wait_cmd_ioc(struct sev_device *sev, > > udelay(10); > } > - > return -ETIMEDOUT; > } > > @@ -1654,7 +1653,7 @@ static int sev_update_firmware(struct device *dev) > return ret; > } > > -static int __sev_snp_shutdown_locked(int *error, bool in_panic) > +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; > @@ -1673,7 +1672,7 @@ static int __sev_snp_shutdown_locked(int *error, bool in_panic) > * In that case, a wbinvd() is done on remote CPUs via the NMI > * callback, so only a local wbinvd() is needed here. > */ > - if (!in_panic) > + if (!panic) > wbinvd_on_all_cpus(); > else > wbinvd(); > @@ -2199,26 +2198,13 @@ int sev_dev_init(struct psp_device *psp) > return ret; > } > > -static void __sev_firmware_shutdown(struct sev_device *sev, bool in_panic) > +static void __sev_firmware_shutdown(struct sev_device *sev, bool panic) > { > int error; > > __sev_platform_shutdown_locked(NULL); > > if (sev_es_tmr) { > - /* > - * 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, so a local wbinvd() is sufficient here. > - */ > - if (!in_panic) > - wbinvd_on_all_cpus(); > - else > - wbinvd(); > - > __snp_free_firmware_pages(virt_to_page(sev_es_tmr), > get_order(sev_es_tmr_size), > true); > @@ -2237,7 +2223,7 @@ static void __sev_firmware_shutdown(struct sev_device *sev, bool in_panic) > snp_range_list = NULL; > } > > - __sev_snp_shutdown_locked(&error, in_panic); > + __sev_snp_shutdown_locked(&error, panic); > } > > static void sev_firmware_shutdown(struct sev_device *sev) > @@ -2262,26 +2248,18 @@ void sev_dev_destroy(struct psp_device *psp) > psp_clear_sev_irq_handler(psp); > } > > -static int sev_snp_shutdown_on_panic(struct notifier_block *nb, > - unsigned long reason, void *arg) > +static int snp_shutdown_on_panic(struct notifier_block *nb, > + unsigned long reason, void *arg) > { > struct sev_device *sev = psp_master->sev_data; > > - /* > - * Panic callbacks are executed with all other CPUs stopped, > - * so don't wait for sev_cmd_mutex to be released since it > - * would block here forever. > - */ > - if (mutex_is_locked(&sev_cmd_mutex)) > - return NOTIFY_DONE; > - > __sev_firmware_shutdown(sev, true); > > return NOTIFY_DONE; > } > > -static struct notifier_block sev_snp_panic_notifier = { > - .notifier_call = sev_snp_shutdown_on_panic, > +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, > @@ -2322,7 +2300,7 @@ void sev_pci_init(void) > "-SNP" : "", sev->api_major, sev->api_minor, sev->build); > > atomic_notifier_chain_register(&panic_notifier_list, > - &sev_snp_panic_notifier); > + &snp_panic_notifier); > return; > > err: > @@ -2339,5 +2317,5 @@ void sev_pci_exit(void) > sev_firmware_shutdown(sev); > > atomic_notifier_chain_unregister(&panic_notifier_list, > - &sev_snp_panic_notifier); > + &snp_panic_notifier); > } > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette >
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index cbffb27f6468..b8c44c492d43 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -59,6 +59,13 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs) */ cpu_emergency_stop_pt(); + /* + * for SNP do wbinvd() on remote CPUs to + * safely do SNP_SHUTDOWN on the local CPU. + */ + if (cpu_feature_enabled(X86_FEATURE_SEV_SNP)) + wbinvd(); + disable_local_APIC(); } diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 9792c7af3005..598878e760bc 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -21,6 +21,7 @@ #include <linux/hw_random.h> #include <linux/ccp.h> #include <linux/firmware.h> +#include <linux/panic_notifier.h> #include <linux/gfp.h> #include <linux/cpufeature.h> #include <linux/fs.h> @@ -144,6 +145,26 @@ 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) @@ -1358,17 +1379,6 @@ 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; @@ -1644,7 +1654,7 @@ static int sev_update_firmware(struct device *dev) return ret; } -static int __sev_snp_shutdown_locked(int *error) +static int __sev_snp_shutdown_locked(int *error, bool in_panic) { struct sev_device *sev = psp_master->sev_data; struct sev_data_snp_shutdown_ex data; @@ -1657,7 +1667,16 @@ static int __sev_snp_shutdown_locked(int *error) data.length = 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 (!in_panic) + wbinvd_on_all_cpus(); + else + wbinvd(); ret = __sev_do_cmd_locked(SEV_CMD_SNP_SHUTDOWN_EX, &data, error); /* SHUTDOWN may require DF_FLUSH */ @@ -1701,17 +1720,6 @@ 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; @@ -2191,19 +2199,29 @@ int sev_dev_init(struct psp_device *psp) return ret; } -static void sev_firmware_shutdown(struct sev_device *sev) +static void __sev_firmware_shutdown(struct sev_device *sev, bool in_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, so a local wbinvd() is sufficient here. + */ + if (!in_panic) + wbinvd_on_all_cpus(); + else + wbinvd(); __snp_free_firmware_pages(virt_to_page(sev_es_tmr), get_order(sev_es_tmr_size), - false); + true); sev_es_tmr = NULL; } @@ -2219,7 +2237,14 @@ static void sev_firmware_shutdown(struct sev_device *sev) snp_range_list = NULL; } - sev_snp_shutdown(&error); + __sev_snp_shutdown_locked(&error, in_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) @@ -2237,6 +2262,28 @@ void sev_dev_destroy(struct psp_device *psp) psp_clear_sev_irq_handler(psp); } +static int sev_snp_shutdown_on_panic(struct notifier_block *nb, + unsigned long reason, void *arg) +{ + struct sev_device *sev = psp_master->sev_data; + + /* + * Panic callbacks are executed with all other CPUs stopped, + * so don't wait for sev_cmd_mutex to be released since it + * would block here forever. + */ + if (mutex_is_locked(&sev_cmd_mutex)) + return NOTIFY_DONE; + + __sev_firmware_shutdown(sev, true); + + return NOTIFY_DONE; +} + +static struct notifier_block sev_snp_panic_notifier = { + .notifier_call = sev_snp_shutdown_on_panic, +}; + int sev_issue_cmd_external_user(struct file *filep, unsigned int cmd, void *data, int *error) { @@ -2274,6 +2321,8 @@ 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, + &sev_snp_panic_notifier); return; err: @@ -2288,4 +2337,7 @@ void sev_pci_exit(void) return; sev_firmware_shutdown(sev); + + atomic_notifier_chain_unregister(&panic_notifier_list, + &sev_snp_panic_notifier); }