diff options
| -rw-r--r-- | arch/x86/coco/sev/Makefile | 5 | ||||
| -rw-r--r-- | arch/x86/coco/sev/core.c | 89 | ||||
| -rw-r--r-- | arch/x86/coco/sev/sev-nmi.c | 108 |
3 files changed, 112 insertions, 90 deletions
diff --git a/arch/x86/coco/sev/Makefile b/arch/x86/coco/sev/Makefile index dcb06dc8b5ae..bc4baa400c55 100644 --- a/arch/x86/coco/sev/Makefile +++ b/arch/x86/coco/sev/Makefile @@ -1,6 +1,6 @@ # SPDX-License-Identifier: GPL-2.0 -obj-y += core.o +obj-y += core.o sev-nmi.o # jump tables are emitted using absolute references in non-PIC code # so they cannot be used in the early SEV startup code @@ -20,3 +20,6 @@ KCSAN_SANITIZE := n # Clang 14 and older may fail to respect __no_sanitize_undefined when inlining UBSAN_SANITIZE := n + +# GCC may fail to respect __no_sanitize_address when inlining +KASAN_SANITIZE_sev-nmi.o := n diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index aeb7731862c0..c7a0f3a2f4ac 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -113,77 +113,6 @@ DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa); DEFINE_PER_CPU(struct svsm_ca *, svsm_caa); DEFINE_PER_CPU(u64, svsm_caa_pa); -static __always_inline bool on_vc_stack(struct pt_regs *regs) -{ - unsigned long sp = regs->sp; - - /* User-mode RSP is not trusted */ - if (user_mode(regs)) - return false; - - /* SYSCALL gap still has user-mode RSP */ - if (ip_within_syscall_gap(regs)) - return false; - - return ((sp >= __this_cpu_ist_bottom_va(VC)) && (sp < __this_cpu_ist_top_va(VC))); -} - -/* - * This function handles the case when an NMI is raised in the #VC - * exception handler entry code, before the #VC handler has switched off - * its IST stack. In this case, the IST entry for #VC must be adjusted, - * so that any nested #VC exception will not overwrite the stack - * contents of the interrupted #VC handler. - * - * The IST entry is adjusted unconditionally so that it can be also be - * unconditionally adjusted back in __sev_es_ist_exit(). Otherwise a - * nested sev_es_ist_exit() call may adjust back the IST entry too - * early. - * - * The __sev_es_ist_enter() and __sev_es_ist_exit() functions always run - * on the NMI IST stack, as they are only called from NMI handling code - * right now. - */ -void noinstr __sev_es_ist_enter(struct pt_regs *regs) -{ - unsigned long old_ist, new_ist; - - /* Read old IST entry */ - new_ist = old_ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]); - - /* - * If NMI happened while on the #VC IST stack, set the new IST - * value below regs->sp, so that the interrupted stack frame is - * not overwritten by subsequent #VC exceptions. - */ - if (on_vc_stack(regs)) - new_ist = regs->sp; - - /* - * Reserve additional 8 bytes and store old IST value so this - * adjustment can be unrolled in __sev_es_ist_exit(). - */ - new_ist -= sizeof(old_ist); - *(unsigned long *)new_ist = old_ist; - - /* Set new IST entry */ - this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], new_ist); -} - -void noinstr __sev_es_ist_exit(void) -{ - unsigned long ist; - - /* Read IST entry */ - ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]); - - if (WARN_ON(ist == __this_cpu_ist_top_va(VC))) - return; - - /* Read back old IST entry and write it to the TSS */ - this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], *(unsigned long *)ist); -} - /* * Nothing shall interrupt this code path while holding the per-CPU * GHCB. The backup GHCB is only for NMIs interrupting this path. @@ -608,24 +537,6 @@ int svsm_perform_call_protocol(struct svsm_call *call) return ret; } -void noinstr __sev_es_nmi_complete(void) -{ - struct ghcb_state state; - struct ghcb *ghcb; - - ghcb = __sev_get_ghcb(&state); - - vc_ghcb_invalidate(ghcb); - ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_NMI_COMPLETE); - ghcb_set_sw_exit_info_1(ghcb, 0); - ghcb_set_sw_exit_info_2(ghcb, 0); - - sev_es_wr_ghcb_msr(__pa_nodebug(ghcb)); - VMGEXIT(); - - __sev_put_ghcb(&state); -} - static u64 __init get_snp_jump_table_addr(void) { struct snp_secrets_page *secrets; diff --git a/arch/x86/coco/sev/sev-nmi.c b/arch/x86/coco/sev/sev-nmi.c new file mode 100644 index 000000000000..d8dfaddfb367 --- /dev/null +++ b/arch/x86/coco/sev/sev-nmi.c @@ -0,0 +1,108 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * AMD Memory Encryption Support + * + * Copyright (C) 2019 SUSE + * + * Author: Joerg Roedel <jroedel@suse.de> + */ + +#define pr_fmt(fmt) "SEV: " fmt + +#include <linux/bug.h> +#include <linux/kernel.h> + +#include <asm/cpu_entry_area.h> +#include <asm/msr.h> +#include <asm/ptrace.h> +#include <asm/sev.h> +#include <asm/sev-internal.h> + +static __always_inline bool on_vc_stack(struct pt_regs *regs) +{ + unsigned long sp = regs->sp; + + /* User-mode RSP is not trusted */ + if (user_mode(regs)) + return false; + + /* SYSCALL gap still has user-mode RSP */ + if (ip_within_syscall_gap(regs)) + return false; + + return ((sp >= __this_cpu_ist_bottom_va(VC)) && (sp < __this_cpu_ist_top_va(VC))); +} + +/* + * This function handles the case when an NMI is raised in the #VC + * exception handler entry code, before the #VC handler has switched off + * its IST stack. In this case, the IST entry for #VC must be adjusted, + * so that any nested #VC exception will not overwrite the stack + * contents of the interrupted #VC handler. + * + * The IST entry is adjusted unconditionally so that it can be also be + * unconditionally adjusted back in __sev_es_ist_exit(). Otherwise a + * nested sev_es_ist_exit() call may adjust back the IST entry too + * early. + * + * The __sev_es_ist_enter() and __sev_es_ist_exit() functions always run + * on the NMI IST stack, as they are only called from NMI handling code + * right now. + */ +void noinstr __sev_es_ist_enter(struct pt_regs *regs) +{ + unsigned long old_ist, new_ist; + + /* Read old IST entry */ + new_ist = old_ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]); + + /* + * If NMI happened while on the #VC IST stack, set the new IST + * value below regs->sp, so that the interrupted stack frame is + * not overwritten by subsequent #VC exceptions. + */ + if (on_vc_stack(regs)) + new_ist = regs->sp; + + /* + * Reserve additional 8 bytes and store old IST value so this + * adjustment can be unrolled in __sev_es_ist_exit(). + */ + new_ist -= sizeof(old_ist); + *(unsigned long *)new_ist = old_ist; + + /* Set new IST entry */ + this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], new_ist); +} + +void noinstr __sev_es_ist_exit(void) +{ + unsigned long ist; + + /* Read IST entry */ + ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]); + + if (WARN_ON(ist == __this_cpu_ist_top_va(VC))) + return; + + /* Read back old IST entry and write it to the TSS */ + this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], *(unsigned long *)ist); +} + +void noinstr __sev_es_nmi_complete(void) +{ + struct ghcb_state state; + struct ghcb *ghcb; + + ghcb = __sev_get_ghcb(&state); + + vc_ghcb_invalidate(ghcb); + ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_NMI_COMPLETE); + ghcb_set_sw_exit_info_1(ghcb, 0); + ghcb_set_sw_exit_info_2(ghcb, 0); + + sev_es_wr_ghcb_msr(__pa_nodebug(ghcb)); + VMGEXIT(); + + __sev_put_ghcb(&state); +} |