Commit 29dcc60f authored by Joerg Roedel's avatar Joerg Roedel Committed by Borislav Petkov

x86/boot/compressed/64: Add stage1 #VC handler

Add the first handler for #VC exceptions. At stage 1 there is no GHCB
yet because the kernel might still be running on the EFI page table.

The stage 1 handler is limited to the MSR-based protocol to talk to the
hypervisor and can only support CPUID exit-codes, but that is enough to
get to stage 2.

 [ bp: Zap superfluous newlines after rd/wrmsr instruction mnemonics. ]
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-20-joro@8bytes.org
parent 21cf2372
......@@ -88,6 +88,7 @@ ifdef CONFIG_X86_64
vmlinux-objs-y += $(obj)/idt_64.o $(obj)/idt_handlers_64.o
vmlinux-objs-y += $(obj)/mem_encrypt.o
vmlinux-objs-y += $(obj)/pgtable_64.o
vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/sev-es.o
endif
vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o
......
......@@ -32,6 +32,10 @@ void load_stage1_idt(void)
{
boot_idt_desc.address = (unsigned long)boot_idt;
if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT))
set_idt_entry(X86_TRAP_VC, boot_stage1_vc);
load_boot_idt(&boot_idt_desc);
}
......
......@@ -70,3 +70,7 @@ SYM_FUNC_END(\name)
.code64
EXCEPTION_HANDLER boot_page_fault do_boot_page_fault error_code=1
#ifdef CONFIG_AMD_MEM_ENCRYPT
EXCEPTION_HANDLER boot_stage1_vc do_vc_no_ghcb error_code=1
#endif
......@@ -141,5 +141,6 @@ extern struct desc_ptr boot_idt_desc;
/* IDT Entry Points */
void boot_page_fault(void);
void boot_stage1_vc(void);
#endif /* BOOT_COMPRESSED_MISC_H */
// SPDX-License-Identifier: GPL-2.0
/*
* AMD Encrypted Register State Support
*
* Author: Joerg Roedel <jroedel@suse.de>
*/
/*
* misc.h needs to be first because it knows how to include the other kernel
* headers in the pre-decompression code in a way that does not break
* compilation.
*/
#include "misc.h"
#include <asm/sev-es.h>
#include <asm/msr-index.h>
#include <asm/ptrace.h>
#include <asm/svm.h>
static inline u64 sev_es_rd_ghcb_msr(void)
{
unsigned long low, high;
asm volatile("rdmsr" : "=a" (low), "=d" (high) :
"c" (MSR_AMD64_SEV_ES_GHCB));
return ((high << 32) | low);
}
static inline void sev_es_wr_ghcb_msr(u64 val)
{
u32 low, high;
low = val & 0xffffffffUL;
high = val >> 32;
asm volatile("wrmsr" : : "c" (MSR_AMD64_SEV_ES_GHCB),
"a"(low), "d" (high) : "memory");
}
#undef __init
#define __init
/* Include code for early handlers */
#include "../../kernel/sev-es-shared.c"
......@@ -466,6 +466,7 @@
#define MSR_AMD64_IBSBRTARGET 0xc001103b
#define MSR_AMD64_IBSOPDATA4 0xc001103d
#define MSR_AMD64_IBS_REG_COUNT_MAX 8 /* includes MSR_AMD64_IBSBRTARGET */
#define MSR_AMD64_SEV_ES_GHCB 0xc0010130
#define MSR_AMD64_SEV 0xc0010131
#define MSR_AMD64_SEV_ENABLED_BIT 0
#define MSR_AMD64_SEV_ENABLED BIT_ULL(MSR_AMD64_SEV_ENABLED_BIT)
......
/* SPDX-License-Identifier: GPL-2.0 */
/*
* AMD Encrypted Register State Support
*
* Author: Joerg Roedel <jroedel@suse.de>
*/
#ifndef __ASM_ENCRYPTED_STATE_H
#define __ASM_ENCRYPTED_STATE_H
#include <linux/types.h>
#define GHCB_SEV_CPUID_REQ 0x004UL
#define GHCB_CPUID_REQ_EAX 0
#define GHCB_CPUID_REQ_EBX 1
#define GHCB_CPUID_REQ_ECX 2
#define GHCB_CPUID_REQ_EDX 3
#define GHCB_CPUID_REQ(fn, reg) (GHCB_SEV_CPUID_REQ | \
(((unsigned long)reg & 3) << 30) | \
(((unsigned long)fn) << 32))
#define GHCB_SEV_CPUID_RESP 0x005UL
#define GHCB_SEV_TERMINATE 0x100UL
#define GHCB_SEV_GHCB_RESP_CODE(v) ((v) & 0xfff)
#define VMGEXIT() { asm volatile("rep; vmmcall\n\r"); }
void do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code);
static inline u64 lower_bits(u64 val, unsigned int bits)
{
u64 mask = (1ULL << bits) - 1;
return (val & mask);
}
#endif
......@@ -26,6 +26,7 @@
#define X86_TRAP_XF 19 /* SIMD Floating-Point Exception */
#define X86_TRAP_VE 20 /* Virtualization Exception */
#define X86_TRAP_CP 21 /* Control Protection Exception */
#define X86_TRAP_VC 29 /* VMM Communication Exception */
#define X86_TRAP_IRET 32 /* IRET Exception */
#endif
// SPDX-License-Identifier: GPL-2.0
/*
* AMD Encrypted Register State Support
*
* Author: Joerg Roedel <jroedel@suse.de>
*
* This file is not compiled stand-alone. It contains code shared
* between the pre-decompression boot code and the running Linux kernel
* and is included directly into both code-bases.
*/
/*
* Boot VC Handler - This is the first VC handler during boot, there is no GHCB
* page yet, so it only supports the MSR based communication with the
* hypervisor and only the CPUID exit-code.
*/
void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code)
{
unsigned int fn = lower_bits(regs->ax, 32);
unsigned long val;
/* Only CPUID is supported via MSR protocol */
if (exit_code != SVM_EXIT_CPUID)
goto fail;
sev_es_wr_ghcb_msr(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_EAX));
VMGEXIT();
val = sev_es_rd_ghcb_msr();
if (GHCB_SEV_GHCB_RESP_CODE(val) != GHCB_SEV_CPUID_RESP)
goto fail;
regs->ax = val >> 32;
sev_es_wr_ghcb_msr(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_EBX));
VMGEXIT();
val = sev_es_rd_ghcb_msr();
if (GHCB_SEV_GHCB_RESP_CODE(val) != GHCB_SEV_CPUID_RESP)
goto fail;
regs->bx = val >> 32;
sev_es_wr_ghcb_msr(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_ECX));
VMGEXIT();
val = sev_es_rd_ghcb_msr();
if (GHCB_SEV_GHCB_RESP_CODE(val) != GHCB_SEV_CPUID_RESP)
goto fail;
regs->cx = val >> 32;
sev_es_wr_ghcb_msr(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_EDX));
VMGEXIT();
val = sev_es_rd_ghcb_msr();
if (GHCB_SEV_GHCB_RESP_CODE(val) != GHCB_SEV_CPUID_RESP)
goto fail;
regs->dx = val >> 32;
/* Skip over the CPUID two-byte opcode */
regs->ip += 2;
return;
fail:
sev_es_wr_ghcb_msr(GHCB_SEV_TERMINATE);
VMGEXIT();
/* Shouldn't get here - if we do halt the machine */
while (true)
asm volatile("hlt\n");
}
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