From: Joerg Roedel <jroedel@xxxxxxx> Setup an early handler for #VC exceptions. There is no GHCB mapped yet, so just re-use the vc_no_ghcb_handler. It can only handle CPUID exit-codes, but that should be enough to get the kernel through verify_cpu() and __startup_64() until it runs on virtual addresses. Signed-off-by: Joerg Roedel <jroedel@xxxxxxx> Link: https://lore.kernel.org/r/20200724160336.5435-42-joro@xxxxxxxxxx --- arch/x86/include/asm/setup.h | 1 + arch/x86/include/asm/sev-es.h | 3 +++ arch/x86/kernel/head64.c | 1 + arch/x86/kernel/head_64.S | 34 +++++++++++++++++++++++++++++++++ arch/x86/kernel/idt.c | 36 +++++++++++++++++++++++++++++++++++ 5 files changed, 75 insertions(+) diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h index cafae86813ae..0ce6453c9272 100644 --- a/arch/x86/include/asm/setup.h +++ b/arch/x86/include/asm/setup.h @@ -53,6 +53,7 @@ extern unsigned long __startup_secondary_64(void); extern void startup_64_setup_env(unsigned long physbase); extern void early_idt_setup_early_handler(unsigned long physaddr); extern void early_load_idt(void); +extern void early_idt_setup(unsigned long physbase); extern void __init do_early_exception(struct pt_regs *regs, int trapnr); #ifdef CONFIG_X86_INTEL_MID diff --git a/arch/x86/include/asm/sev-es.h b/arch/x86/include/asm/sev-es.h index 7c0807b84546..ec0e112a742b 100644 --- a/arch/x86/include/asm/sev-es.h +++ b/arch/x86/include/asm/sev-es.h @@ -73,4 +73,7 @@ static inline u64 lower_bits(u64 val, unsigned int bits) return (val & mask); } +/* Early IDT entry points for #VC handler */ +extern void vc_no_ghcb(void); + #endif diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 41514ec1e6f0..250fae33bf66 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -39,6 +39,7 @@ #include <asm/realmode.h> #include <asm/extable.h> #include <asm/trapnr.h> +#include <asm/sev-es.h> /* * Manage page tables very early on. diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 4622940134a5..12bf6f11fd83 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -95,6 +95,13 @@ SYM_CODE_START_NOALIGN(startup_64) .Lon_kernel_cs: UNWIND_HINT_EMPTY + /* Setup IDT - Needed for SEV-ES */ + pushq %rsi + /* early_idt_setup - physbase as first parameter */ + leaq _text(%rip), %rdi + call early_idt_setup + popq %rsi + /* Sanitize CPU configuration */ call verify_cpu @@ -363,6 +370,33 @@ SYM_CODE_START_LOCAL(early_idt_handler_common) jmp restore_regs_and_return_to_kernel SYM_CODE_END(early_idt_handler_common) +#ifdef CONFIG_AMD_MEM_ENCRYPT +/* + * VC Exception handler used during very early boot. The + * early_idt_handler_array can't be used because it returns via the + * paravirtualized INTERRUPT_RETURN and pv-ops don't work that early. + */ +SYM_CODE_START_NOALIGN(vc_no_ghcb) + UNWIND_HINT_IRET_REGS offset=8 + + /* Build pt_regs */ + PUSH_AND_CLEAR_REGS + + /* Call C handler */ + movq %rsp, %rdi + movq ORIG_RAX(%rsp), %rsi + call do_vc_no_ghcb + + /* Unwind pt_regs */ + POP_REGS + + /* Remove Error Code */ + addq $8, %rsp + + /* Pure iret required here - don't use INTERRUPT_RETURN */ + iretq +SYM_CODE_END(vc_no_ghcb) +#endif #define SYM_DATA_START_PAGE_ALIGNED(name) \ SYM_START(name, SYM_L_GLOBAL, .balign PAGE_SIZE) diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c index e2777cc264f5..0d560a1218e1 100644 --- a/arch/x86/kernel/idt.c +++ b/arch/x86/kernel/idt.c @@ -11,6 +11,7 @@ #include <asm/desc.h> #include <asm/hw_irq.h> #include <asm/setup.h> +#include <asm/sev-es.h> struct idt_data { unsigned int vector; @@ -408,3 +409,38 @@ void early_load_idt(void) { load_idt(&idt_descr); } + +#ifdef CONFIG_AMD_MEM_ENCRYPT +static void set_early_idt_handler(gate_desc *idt, int n, void *handler) +{ + struct idt_data data; + gate_desc desc; + + init_idt_data(&data, n, handler); + idt_init_desc(&desc, &data); + native_write_idt_entry(idt, n, &desc); +} +#endif + +static struct desc_ptr early_idt_descr __initdata = { + .size = IDT_TABLE_SIZE - 1, + .address = 0 /* Needs physical address of idt_table - initialized at runtime. */, +}; + +void __init early_idt_setup(unsigned long physbase) +{ + void __maybe_unused *handler; + gate_desc *idt; + + idt = fixup_pointer(idt_table, physbase); + +#ifdef CONFIG_AMD_MEM_ENCRYPT + /* VMM Communication Exception */ + handler = fixup_pointer(vc_no_ghcb, physbase); + set_early_idt_handler(idt, X86_TRAP_VC, handler); +#endif + + /* Initialize IDT descriptor and load IDT */ + early_idt_descr.address = (unsigned long)idt; + native_load_idt(&early_idt_descr); +} -- 2.28.0 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
