From: Joerg Roedel <[email protected]> Add the infrastructure to handle #VC exceptions when the kernel runs on virtual addresses and has a GHCB mapped. This handler will be used until the runtime #VC handler takes over.
Signed-off-by: Joerg Roedel <[email protected]> --- arch/x86/include/asm/segment.h | 2 +- arch/x86/include/asm/sev-es.h | 1 + arch/x86/kernel/head64.c | 5 ++ arch/x86/kernel/sev-es-shared.c | 15 ++--- arch/x86/kernel/sev-es.c | 116 ++++++++++++++++++++++++++++++++ arch/x86/mm/extable.c | 1 + 6 files changed, 131 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index 6669164abadc..5b648066504c 100644 --- a/arch/x86/include/asm/segment.h +++ b/arch/x86/include/asm/segment.h @@ -230,7 +230,7 @@ #define NUM_EXCEPTION_VECTORS 32 /* Bitmask of exception vectors which push an error code on the stack: */ -#define EXCEPTION_ERRCODE_MASK 0x00027d00 +#define EXCEPTION_ERRCODE_MASK 0x20027d00 #define GDT_SIZE (GDT_ENTRIES*8) #define GDT_ENTRY_TLS_ENTRIES 3 diff --git a/arch/x86/include/asm/sev-es.h b/arch/x86/include/asm/sev-es.h index caa29f75ce41..a2d0c77dabc3 100644 --- a/arch/x86/include/asm/sev-es.h +++ b/arch/x86/include/asm/sev-es.h @@ -76,5 +76,6 @@ static inline u64 copy_lower_bits(u64 out, u64 in, unsigned int bits) } extern void early_vc_handler(void); +extern int boot_vc_exception(struct pt_regs *regs); #endif diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index eab04ac260d4..14e0699b2692 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -390,6 +390,11 @@ void __init early_exception(struct pt_regs *regs, int trapnr) cr2 = native_read_cr2(); r = early_make_pgtable(cr2); break; +#ifdef CONFIG_AMD_MEM_ENCRYPT + case X86_TRAP_VC: + r = boot_vc_exception(regs); + break; +#endif default: r = 1; } diff --git a/arch/x86/kernel/sev-es-shared.c b/arch/x86/kernel/sev-es-shared.c index ad2a6c964217..57c29c91fe87 100644 --- a/arch/x86/kernel/sev-es-shared.c +++ b/arch/x86/kernel/sev-es-shared.c @@ -9,7 +9,7 @@ * and is included directly into both code-bases. */ -static void __maybe_unused terminate(unsigned int reason) +static void terminate(unsigned int reason) { /* Request Guest Termination from Hypvervisor */ write_ghcb_msr(GHCB_SEV_TERMINATE); @@ -19,7 +19,7 @@ static void __maybe_unused terminate(unsigned int reason) asm volatile("hlt\n" : : : "memory"); } -static bool __maybe_unused sev_es_negotiate_protocol(void) +static bool sev_es_negotiate_protocol(void) { u64 val; @@ -38,7 +38,7 @@ static bool __maybe_unused sev_es_negotiate_protocol(void) return true; } -static void __maybe_unused ghcb_invalidate(struct ghcb *ghcb) +static void ghcb_invalidate(struct ghcb *ghcb) { memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap)); } @@ -80,10 +80,9 @@ static bool decoding_needed(unsigned long exit_code) exit_code <= SVM_EXIT_LAST_EXCP); } -static enum es_result __maybe_unused -init_em_ctxt(struct es_em_ctxt *ctxt, - struct pt_regs *regs, - unsigned long exit_code) +static enum es_result init_em_ctxt(struct es_em_ctxt *ctxt, + struct pt_regs *regs, + unsigned long exit_code) { enum es_result ret = ES_OK; @@ -96,7 +95,7 @@ init_em_ctxt(struct es_em_ctxt *ctxt, return ret; } -static void __maybe_unused finish_insn(struct es_em_ctxt *ctxt) +static void finish_insn(struct es_em_ctxt *ctxt) { ctxt->regs->ip += ctxt->insn.length; } diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index 33ab7fe8b6a0..0e0b28477627 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -7,15 +7,30 @@ * Author: Joerg Roedel <[email protected]> */ +#include <linux/sched/debug.h> /* For show_regs() */ #include <linux/kernel.h> +#include <linux/printk.h> #include <linux/mm.h> #include <asm/trap_defs.h> #include <asm/sev-es.h> #include <asm/fpu/internal.h> #include <asm/processor.h> +#include <asm/trap_defs.h> #include <asm/svm.h> +/* For early boot hypervisor communication in SEV-ES enabled guests */ +struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE); + +/* + * Needs to be in the .data section because we need it NULL before bss is + * cleared + */ +struct ghcb __initdata *boot_ghcb; + +/* Needed in early_forward_exception */ +extern void early_exception(struct pt_regs *regs, int trapnr); + static inline u64 read_ghcb_msr(void) { return native_read_msr(MSR_AMD64_SEV_ES_GHCB); @@ -96,3 +111,104 @@ static phys_addr_t es_slow_virt_to_phys(struct ghcb *ghcb, long vaddr) /* Include code shared with pre-decompression boot stage */ #include "sev-es-shared.c" + +/* + * This function runs on the first #VC exception after the kernel + * switched to virtual addresses. + */ +static bool __init setup_ghcb(void) +{ + /* First make sure the hypervisor talks a supported protocol. */ + if (!sev_es_negotiate_protocol()) + return false; + /* + * Clear the boot_ghcb. The first exception comes in before the bss + * section is cleared. + */ + memset(&boot_ghcb_page, 0, PAGE_SIZE); + + /* Alright - Make the boot-ghcb public */ + boot_ghcb = &boot_ghcb_page; + + return true; +} + +static void __init early_forward_exception(struct es_em_ctxt *ctxt) +{ + int trapnr = ctxt->fi.vector; + + if (trapnr == X86_TRAP_PF) + native_write_cr2(ctxt->fi.cr2); + + ctxt->regs->orig_ax = ctxt->fi.error_code; + early_exception(ctxt->regs, trapnr); +} + +static enum es_result handle_vc_exception(struct es_em_ctxt *ctxt, + struct ghcb *ghcb, + unsigned long exit_code) +{ + enum es_result result; + + switch (exit_code) { + default: + /* + * Unexpected #VC exception + */ + result = ES_UNSUPPORTED; + } + + return result; +} + +int __init boot_vc_exception(struct pt_regs *regs) +{ + unsigned long exit_code = regs->orig_ax; + struct es_em_ctxt ctxt; + enum es_result result; + + /* Do initial setup or terminate the guest */ + if (unlikely(boot_ghcb == NULL && !setup_ghcb())) + terminate(GHCB_SEV_ES_REASON_GENERAL_REQUEST); + + ghcb_invalidate(boot_ghcb); + result = init_em_ctxt(&ctxt, regs, exit_code); + + if (result == ES_OK) + result = handle_vc_exception(&ctxt, boot_ghcb, exit_code); + + /* Done - now check the result */ + switch (result) { + case ES_OK: + finish_insn(&ctxt); + break; + case ES_UNSUPPORTED: + early_printk("PANIC: Unsupported exit-code 0x%02lx in early #VC exception (IP: 0x%lx)\n", + exit_code, regs->ip); + goto fail; + case ES_VMM_ERROR: + early_printk("PANIC: Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n", + exit_code, regs->ip); + goto fail; + case ES_DECODE_FAILED: + early_printk("PANIC: Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n", + exit_code, regs->ip); + goto fail; + case ES_EXCEPTION: + early_forward_exception(&ctxt); + break; + case ES_RETRY: + /* Nothing to do */ + break; + default: + BUG(); + } + + return 0; + +fail: + show_regs(regs); + + while (true) + halt(); +} diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 30bb0bd3b1b8..cd440a9cf422 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -5,6 +5,7 @@ #include <xen/xen.h> #include <asm/fpu/internal.h> +#include <asm/sev-es.h> #include <asm/traps.h> #include <asm/kdebug.h> -- 2.17.1 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
