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|
// 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.
*/
#include <asm/setup_data.h>
#ifndef __BOOT_COMPRESSED
#define error(v) pr_err(v)
#define has_cpuflag(f) boot_cpu_has(f)
#else
#undef WARN
#define WARN(condition, format...) (!!(condition))
#endif
/* I/O parameters for CPUID-related helpers */
struct cpuid_leaf {
u32 fn;
u32 subfn;
u32 eax;
u32 ebx;
u32 ecx;
u32 edx;
};
/*
* Individual entries of the SNP CPUID table, as defined by the SNP
* Firmware ABI, Revision 0.9, Section 7.1, Table 14.
*/
struct snp_cpuid_fn {
u32 eax_in;
u32 ecx_in;
u64 xcr0_in;
u64 xss_in;
u32 eax;
u32 ebx;
u32 ecx;
u32 edx;
u64 __reserved;
} __packed;
/*
* SNP CPUID table, as defined by the SNP Firmware ABI, Revision 0.9,
* Section 8.14.2.6. Also noted there is the SNP firmware-enforced limit
* of 64 entries per CPUID table.
*/
#define SNP_CPUID_COUNT_MAX 64
struct snp_cpuid_table {
u32 count;
u32 __reserved1;
u64 __reserved2;
struct snp_cpuid_fn fn[SNP_CPUID_COUNT_MAX];
} __packed;
/*
* Since feature negotiation related variables are set early in the boot
* process they must reside in the .data section so as not to be zeroed
* out when the .bss section is later cleared.
*
* GHCB protocol version negotiated with the hypervisor.
*/
static u16 ghcb_version __ro_after_init;
/* Copy of the SNP firmware's CPUID page. */
static struct snp_cpuid_table cpuid_table_copy __ro_after_init;
/*
* These will be initialized based on CPUID table so that non-present
* all-zero leaves (for sparse tables) can be differentiated from
* invalid/out-of-range leaves. This is needed since all-zero leaves
* still need to be post-processed.
*/
static u32 cpuid_std_range_max __ro_after_init;
static u32 cpuid_hyp_range_max __ro_after_init;
static u32 cpuid_ext_range_max __ro_after_init;
static bool __init sev_es_check_cpu_features(void)
{
if (!has_cpuflag(X86_FEATURE_RDRAND)) {
error("RDRAND instruction not supported - no trusted source of randomness available\n");
return false;
}
return true;
}
static void __noreturn sev_es_terminate(unsigned int set, unsigned int reason)
{
u64 val = GHCB_MSR_TERM_REQ;
/* Tell the hypervisor what went wrong. */
val |= GHCB_SEV_TERM_REASON(set, reason);
/* Request Guest Termination from Hypervisor */
sev_es_wr_ghcb_msr(val);
VMGEXIT();
while (true)
asm volatile("hlt\n" : : : "memory");
}
/*
* The hypervisor features are available from GHCB version 2 onward.
*/
static u64 get_hv_features(void)
{
u64 val;
if (ghcb_version < 2)
return 0;
sev_es_wr_ghcb_msr(GHCB_MSR_HV_FT_REQ);
VMGEXIT();
val = sev_es_rd_ghcb_msr();
if (GHCB_RESP_CODE(val) != GHCB_MSR_HV_FT_RESP)
return 0;
return GHCB_MSR_HV_FT_RESP_VAL(val);
}
static void snp_register_ghcb_early(unsigned long paddr)
{
unsigned long pfn = paddr >> PAGE_SHIFT;
u64 val;
sev_es_wr_ghcb_msr(GHCB_MSR_REG_GPA_REQ_VAL(pfn));
VMGEXIT();
val = sev_es_rd_ghcb_msr();
/* If the response GPA is not ours then abort the guest */
if ((GHCB_RESP_CODE(val) != GHCB_MSR_REG_GPA_RESP) ||
(GHCB_MSR_REG_GPA_RESP_VAL(val) != pfn))
sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_REGISTER);
}
static bool sev_es_negotiate_protocol(void)
{
u64 val;
/* Do the GHCB protocol version negotiation */
sev_es_wr_ghcb_msr(GHCB_MSR_SEV_INFO_REQ);
VMGEXIT();
val = sev_es_rd_ghcb_msr();
if (GHCB_MSR_INFO(val) != GHCB_MSR_SEV_INFO_RESP)
return false;
if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTOCOL_MIN ||
GHCB_MSR_PROTO_MIN(val) > GHCB_PROTOCOL_MAX)
return false;
ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX);
return true;
}
static __always_inline void vc_ghcb_invalidate(struct ghcb *ghcb)
{
ghcb->save.sw_exit_code = 0;
__builtin_memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap));
}
static bool vc_decoding_needed(unsigned long exit_code)
{
/* Exceptions don't require to decode the instruction */
return !(exit_code >= SVM_EXIT_EXCP_BASE &&
exit_code <= SVM_EXIT_LAST_EXCP);
}
static enum es_result vc_init_em_ctxt(struct es_em_ctxt *ctxt,
struct pt_regs *regs,
unsigned long exit_code)
{
enum es_result ret = ES_OK;
memset(ctxt, 0, sizeof(*ctxt));
ctxt->regs = regs;
if (vc_decoding_needed(exit_code))
ret = vc_decode_insn(ctxt);
return ret;
}
static void vc_finish_insn(struct es_em_ctxt *ctxt)
{
ctxt->regs->ip += ctxt->insn.length;
}
static enum es_result verify_exception_info(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
{
u32 ret;
ret = ghcb->save.sw_exit_info_1 & GENMASK_ULL(31, 0);
if (!ret)
return ES_OK;
if (ret == 1) {
u64 info = ghcb->save.sw_exit_info_2;
unsigned long v = info & SVM_EVTINJ_VEC_MASK;
/* Check if exception information from hypervisor is sane. */
if ((info & SVM_EVTINJ_VALID) &&
((v == X86_TRAP_GP) || (v == X86_TRAP_UD)) &&
((info & SVM_EVTINJ_TYPE_MASK) == SVM_EVTINJ_TYPE_EXEPT)) {
ctxt->fi.vector = v;
if (info & SVM_EVTINJ_VALID_ERR)
ctxt->fi.error_code = info >> 32;
return ES_EXCEPTION;
}
}
return ES_VMM_ERROR;
}
static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
struct es_em_ctxt *ctxt,
u64 exit_code, u64 exit_info_1,
u64 exit_info_2)
{
/* Fill in protocol and format specifiers */
ghcb->protocol_version = ghcb_version;
ghcb->ghcb_usage = GHCB_DEFAULT_USAGE;
ghcb_set_sw_exit_code(ghcb, exit_code);
ghcb_set_sw_exit_info_1(ghcb, exit_info_1);
ghcb_set_sw_exit_info_2(ghcb, exit_info_2);
sev_es_wr_ghcb_msr(__pa(ghcb));
VMGEXIT();
return verify_exception_info(ghcb, ctxt);
}
static int __sev_cpuid_hv(u32 fn, int reg_idx, u32 *reg)
{
u64 val;
sev_es_wr_ghcb_msr(GHCB_CPUID_REQ(fn, reg_idx));
VMGEXIT();
val = sev_es_rd_ghcb_msr();
if (GHCB_RESP_CODE(val) != GHCB_MSR_CPUID_RESP)
return -EIO;
*reg = (val >> 32);
return 0;
}
static int __sev_cpuid_hv_msr(struct cpuid_leaf *leaf)
{
int ret;
/*
* MSR protocol does not support fetching non-zero subfunctions, but is
* sufficient to handle current early-boot cases. Should that change,
* make sure to report an error rather than ignoring the index and
* grabbing random values. If this issue arises in the future, handling
* can be added here to use GHCB-page protocol for cases that occur late
* enough in boot that GHCB page is available.
*/
if (cpuid_function_is_indexed(leaf->fn) && leaf->subfn)
return -EINVAL;
ret = __sev_cpuid_hv(leaf->fn, GHCB_CPUID_REQ_EAX, &leaf->eax);
ret = ret ? : __sev_cpuid_hv(leaf->fn, GHCB_CPUID_REQ_EBX, &leaf->ebx);
ret = ret ? : __sev_cpuid_hv(leaf->fn, GHCB_CPUID_REQ_ECX, &leaf->ecx);
ret = ret ? : __sev_cpuid_hv(leaf->fn, GHCB_CPUID_REQ_EDX, &leaf->edx);
return ret;
}
static int __sev_cpuid_hv_ghcb(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
{
u32 cr4 = native_read_cr4();
int ret;
ghcb_set_rax(ghcb, leaf->fn);
ghcb_set_rcx(ghcb, leaf->subfn);
if (cr4 & X86_CR4_OSXSAVE)
/* Safe to read xcr0 */
ghcb_set_xcr0(ghcb, xgetbv(XCR_XFEATURE_ENABLED_MASK));
else
/* xgetbv will cause #UD - use reset value for xcr0 */
ghcb_set_xcr0(ghcb, 1);
ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0);
if (ret != ES_OK)
return ret;
if (!(ghcb_rax_is_valid(ghcb) &&
ghcb_rbx_is_valid(ghcb) &&
ghcb_rcx_is_valid(ghcb) &&
ghcb_rdx_is_valid(ghcb)))
return ES_VMM_ERROR;
leaf->eax = ghcb->save.rax;
leaf->ebx = ghcb->save.rbx;
leaf->ecx = ghcb->save.rcx;
leaf->edx = ghcb->save.rdx;
return ES_OK;
}
static int sev_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
{
return ghcb ? __sev_cpuid_hv_ghcb(ghcb, ctxt, leaf)
: __sev_cpuid_hv_msr(leaf);
}
/*
* This may be called early while still running on the initial identity
* mapping. Use RIP-relative addressing to obtain the correct address
* while running with the initial identity mapping as well as the
* switch-over to kernel virtual addresses later.
*/
static const struct snp_cpuid_table *snp_cpuid_get_table(void)
{
void *ptr;
asm ("lea cpuid_table_copy(%%rip), %0"
: "=r" (ptr)
: "p" (&cpuid_table_copy));
return ptr;
}
/*
* The SNP Firmware ABI, Revision 0.9, Section 7.1, details the use of
* XCR0_IN and XSS_IN to encode multiple versions of 0xD subfunctions 0
* and 1 based on the corresponding features enabled by a particular
* combination of XCR0 and XSS registers so that a guest can look up the
* version corresponding to the features currently enabled in its XCR0/XSS
* registers. The only values that differ between these versions/table
* entries is the enabled XSAVE area size advertised via EBX.
*
* While hypervisors may choose to make use of this support, it is more
* robust/secure for a guest to simply find the entry corresponding to the
* base/legacy XSAVE area size (XCR0=1 or XCR0=3), and then calculate the
* XSAVE area size using subfunctions 2 through 64, as documented in APM
* Volume 3, Rev 3.31, Appendix E.3.8, which is what is done here.
*
* Since base/legacy XSAVE area size is documented as 0x240, use that value
* directly rather than relying on the base size in the CPUID table.
*
* Return: XSAVE area size on success, 0 otherwise.
*/
static u32 snp_cpuid_calc_xsave_size(u64 xfeatures_en, bool compacted)
{
const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
u64 xfeatures_found = 0;
u32 xsave_size = 0x240;
int i;
for (i = 0; i < cpuid_table->count; i++) {
const struct snp_cpuid_fn *e = &cpuid_table->fn[i];
if (!(e->eax_in == 0xD && e->ecx_in > 1 && e->ecx_in < 64))
continue;
if (!(xfeatures_en & (BIT_ULL(e->ecx_in))))
continue;
if (xfeatures_found & (BIT_ULL(e->ecx_in)))
continue;
xfeatures_found |= (BIT_ULL(e->ecx_in));
if (compacted)
xsave_size += e->eax;
else
xsave_size = max(xsave_size, e->eax + e->ebx);
}
/*
* Either the guest set unsupported XCR0/XSS bits, or the corresponding
* entries in the CPUID table were not present. This is not a valid
* state to be in.
*/
if (xfeatures_found != (xfeatures_en & GENMASK_ULL(63, 2)))
return 0;
return xsave_size;
}
static bool
snp_cpuid_get_validated_func(struct cpuid_leaf *leaf)
{
const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
int i;
for (i = 0; i < cpuid_table->count; i++) {
const struct snp_cpuid_fn *e = &cpuid_table->fn[i];
if (e->eax_in != leaf->fn)
continue;
if (cpuid_function_is_indexed(leaf->fn) && e->ecx_in != leaf->subfn)
continue;
/*
* For 0xD subfunctions 0 and 1, only use the entry corresponding
* to the base/legacy XSAVE area size (XCR0=1 or XCR0=3, XSS=0).
* See the comments above snp_cpuid_calc_xsave_size() for more
* details.
*/
if (e->eax_in == 0xD && (e->ecx_in == 0 || e->ecx_in == 1))
if (!(e->xcr0_in == 1 || e->xcr0_in == 3) || e->xss_in)
continue;
leaf->eax = e->eax;
leaf->ebx = e->ebx;
leaf->ecx = e->ecx;
leaf->edx = e->edx;
return true;
}
return false;
}
static void snp_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
{
if (sev_cpuid_hv(ghcb, ctxt, leaf))
sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID_HV);
}
static int snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
struct cpuid_leaf *leaf)
{
struct cpuid_leaf leaf_hv = *leaf;
switch (leaf->fn) {
case 0x1:
snp_cpuid_hv(ghcb, ctxt, &leaf_hv);
/* initial APIC ID */
leaf->ebx = (leaf_hv.ebx & GENMASK(31, 24)) | (leaf->ebx & GENMASK(23, 0));
/* APIC enabled bit */
leaf->edx = (leaf_hv.edx & BIT(9)) | (leaf->edx & ~BIT(9));
/* OSXSAVE enabled bit */
if (native_read_cr4() & X86_CR4_OSXSAVE)
leaf->ecx |= BIT(27);
break;
case 0x7:
/* OSPKE enabled bit */
leaf->ecx &= ~BIT(4);
if (native_read_cr4() & X86_CR4_PKE)
leaf->ecx |= BIT(4);
break;
case 0xB:
leaf_hv.subfn = 0;
snp_cpuid_hv(ghcb, ctxt, &leaf_hv);
/* extended APIC ID */
leaf->edx = leaf_hv.edx;
break;
case 0xD: {
bool compacted = false;
u64 xcr0 = 1, xss = 0;
u32 xsave_size;
if (leaf->subfn != 0 && leaf->subfn != 1)
return 0;
if (native_read_cr4() & X86_CR4_OSXSAVE)
xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
if (leaf->subfn == 1) {
/* Get XSS value if XSAVES is enabled. */
if (leaf->eax & BIT(3)) {
unsigned long lo, hi;
asm volatile("rdmsr" : "=a" (lo), "=d" (hi)
: "c" (MSR_IA32_XSS));
xss = (hi << 32) | lo;
}
/*
* The PPR and APM aren't clear on what size should be
* encoded in 0xD:0x1:EBX when compaction is not enabled
* by either XSAVEC (feature bit 1) or XSAVES (feature
* bit 3) since SNP-capable hardware has these feature
* bits fixed as 1. KVM sets it to 0 in this case, but
* to avoid this becoming an issue it's safer to simply
* treat this as unsupported for SNP guests.
*/
if (!(leaf->eax & (BIT(1) | BIT(3))))
return -EINVAL;
compacted = true;
}
xsave_size = snp_cpuid_calc_xsave_size(xcr0 | xss, compacted);
if (!xsave_size)
return -EINVAL;
leaf->ebx = xsave_size;
}
break;
case 0x8000001E:
snp_cpuid_hv(ghcb, ctxt, &leaf_hv);
/* extended APIC ID */
leaf->eax = leaf_hv.eax;
/* compute ID */
leaf->ebx = (leaf->ebx & GENMASK(31, 8)) | (leaf_hv.ebx & GENMASK(7, 0));
/* node ID */
leaf->ecx = (leaf->ecx & GENMASK(31, 8)) | (leaf_hv.ecx & GENMASK(7, 0));
break;
default:
/* No fix-ups needed, use values as-is. */
break;
}
return 0;
}
/*
* Returns -EOPNOTSUPP if feature not enabled. Any other non-zero return value
* should be treated as fatal by caller.
*/
static int snp_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
{
const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
if (!cpuid_table->count)
return -EOPNOTSUPP;
if (!snp_cpuid_get_validated_func(leaf)) {
/*
* Some hypervisors will avoid keeping track of CPUID entries
* where all values are zero, since they can be handled the
* same as out-of-range values (all-zero). This is useful here
* as well as it allows virtually all guest configurations to
* work using a single SNP CPUID table.
*
* To allow for this, there is a need to distinguish between
* out-of-range entries and in-range zero entries, since the
* CPUID table entries are only a template that may need to be
* augmented with additional values for things like
* CPU-specific information during post-processing. So if it's
* not in the table, set the values to zero. Then, if they are
* within a valid CPUID range, proceed with post-processing
* using zeros as the initial values. Otherwise, skip
* post-processing and just return zeros immediately.
*/
leaf->eax = leaf->ebx = leaf->ecx = leaf->edx = 0;
/* Skip post-processing for out-of-range zero leafs. */
if (!(leaf->fn <= cpuid_std_range_max ||
(leaf->fn >= 0x40000000 && leaf->fn <= cpuid_hyp_range_max) ||
(leaf->fn >= 0x80000000 && leaf->fn <= cpuid_ext_range_max)))
return 0;
}
return snp_cpuid_postprocess(ghcb, ctxt, leaf);
}
/*
* 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 subfn = lower_bits(regs->cx, 32);
unsigned int fn = lower_bits(regs->ax, 32);
struct cpuid_leaf leaf;
int ret;
/* Only CPUID is supported via MSR protocol */
if (exit_code != SVM_EXIT_CPUID)
goto fail;
leaf.fn = fn;
leaf.subfn = subfn;
ret = snp_cpuid(NULL, NULL, &leaf);
if (!ret)
goto cpuid_done;
if (ret != -EOPNOTSUPP)
goto fail;
if (__sev_cpuid_hv_msr(&leaf))
goto fail;
cpuid_done:
regs->ax = leaf.eax;
regs->bx = leaf.ebx;
regs->cx = leaf.ecx;
regs->dx = leaf.edx;
/*
* This is a VC handler and the #VC is only raised when SEV-ES is
* active, which means SEV must be active too. Do sanity checks on the
* CPUID results to make sure the hypervisor does not trick the kernel
* into the no-sev path. This could map sensitive data unencrypted and
* make it accessible to the hypervisor.
*
* In particular, check for:
* - Availability of CPUID leaf 0x8000001f
* - SEV CPUID bit.
*
* The hypervisor might still report the wrong C-bit position, but this
* can't be checked here.
*/
if (fn == 0x80000000 && (regs->ax < 0x8000001f))
/* SEV leaf check */
goto fail;
else if ((fn == 0x8000001f && !(regs->ax & BIT(1))))
/* SEV bit */
goto fail;
/* Skip over the CPUID two-byte opcode */
regs->ip += 2;
return;
fail:
/* Terminate the guest */
sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
}
static enum es_result vc_insn_string_check(struct es_em_ctxt *ctxt,
unsigned long address,
bool write)
{
if (user_mode(ctxt->regs) && fault_in_kernel_space(address)) {
ctxt->fi.vector = X86_TRAP_PF;
ctxt->fi.error_code = X86_PF_USER;
ctxt->fi.cr2 = address;
if (write)
ctxt->fi.error_code |= X86_PF_WRITE;
return ES_EXCEPTION;
}
return ES_OK;
}
static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt,
void *src, char *buf,
unsigned int data_size,
unsigned int count,
bool backwards)
{
int i, b = backwards ? -1 : 1;
unsigned long address = (unsigned long)src;
enum es_result ret;
ret = vc_insn_string_check(ctxt, address, false);
if (ret != ES_OK)
return ret;
for (i = 0; i < count; i++) {
void *s = src + (i * data_size * b);
char *d = buf + (i * data_size);
ret = vc_read_mem(ctxt, s, d, data_size);
if (ret != ES_OK)
break;
}
return ret;
}
static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt,
void *dst, char *buf,
unsigned int data_size,
unsigned int count,
bool backwards)
{
int i, s = backwards ? -1 : 1;
unsigned long address = (unsigned long)dst;
enum es_result ret;
ret = vc_insn_string_check(ctxt, address, true);
if (ret != ES_OK)
return ret;
for (i = 0; i < count; i++) {
void *d = dst + (i * data_size * s);
char *b = buf + (i * data_size);
ret = vc_write_mem(ctxt, d, b, data_size);
if (ret != ES_OK)
break;
}
return ret;
}
#define IOIO_TYPE_STR BIT(2)
#define IOIO_TYPE_IN 1
#define IOIO_TYPE_INS (IOIO_TYPE_IN | IOIO_TYPE_STR)
#define IOIO_TYPE_OUT 0
#define IOIO_TYPE_OUTS (IOIO_TYPE_OUT | IOIO_TYPE_STR)
#define IOIO_REP BIT(3)
#define IOIO_ADDR_64 BIT(9)
#define IOIO_ADDR_32 BIT(8)
#define IOIO_ADDR_16 BIT(7)
#define IOIO_DATA_32 BIT(6)
#define IOIO_DATA_16 BIT(5)
#define IOIO_DATA_8 BIT(4)
#define IOIO_SEG_ES (0 << 10)
#define IOIO_SEG_DS (3 << 10)
static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
{
struct insn *insn = &ctxt->insn;
size_t size;
u64 port;
*exitinfo = 0;
switch (insn->opcode.bytes[0]) {
/* INS opcodes */
case 0x6c:
case 0x6d:
*exitinfo |= IOIO_TYPE_INS;
*exitinfo |= IOIO_SEG_ES;
port = ctxt->regs->dx & 0xffff;
break;
/* OUTS opcodes */
case 0x6e:
case 0x6f:
*exitinfo |= IOIO_TYPE_OUTS;
*exitinfo |= IOIO_SEG_DS;
port = ctxt->regs->dx & 0xffff;
break;
/* IN immediate opcodes */
case 0xe4:
case 0xe5:
*exitinfo |= IOIO_TYPE_IN;
port = (u8)insn->immediate.value & 0xffff;
break;
/* OUT immediate opcodes */
case 0xe6:
case 0xe7:
*exitinfo |= IOIO_TYPE_OUT;
port = (u8)insn->immediate.value & 0xffff;
break;
/* IN register opcodes */
case 0xec:
case 0xed:
*exitinfo |= IOIO_TYPE_IN;
port = ctxt->regs->dx & 0xffff;
break;
/* OUT register opcodes */
case 0xee:
case 0xef:
*exitinfo |= IOIO_TYPE_OUT;
port = ctxt->regs->dx & 0xffff;
break;
default:
return ES_DECODE_FAILED;
}
*exitinfo |= port << 16;
switch (insn->opcode.bytes[0]) {
case 0x6c:
case 0x6e:
case 0xe4:
case 0xe6:
case 0xec:
case 0xee:
/* Single byte opcodes */
*exitinfo |= IOIO_DATA_8;
size = 1;
break;
default:
/* Length determined by instruction parsing */
*exitinfo |= (insn->opnd_bytes == 2) ? IOIO_DATA_16
: IOIO_DATA_32;
size = (insn->opnd_bytes == 2) ? 2 : 4;
}
switch (insn->addr_bytes) {
case 2:
*exitinfo |= IOIO_ADDR_16;
break;
case 4:
*exitinfo |= IOIO_ADDR_32;
break;
case 8:
*exitinfo |= IOIO_ADDR_64;
break;
}
if (insn_has_rep_prefix(insn))
*exitinfo |= IOIO_REP;
return vc_ioio_check(ctxt, (u16)port, size);
}
static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
{
struct pt_regs *regs = ctxt->regs;
u64 exit_info_1, exit_info_2;
enum es_result ret;
ret = vc_ioio_exitinfo(ctxt, &exit_info_1);
if (ret != ES_OK)
return ret;
if (exit_info_1 & IOIO_TYPE_STR) {
/* (REP) INS/OUTS */
bool df = ((regs->flags & X86_EFLAGS_DF) == X86_EFLAGS_DF);
unsigned int io_bytes, exit_bytes;
unsigned int ghcb_count, op_count;
unsigned long es_base;
u64 sw_scratch;
/*
* For the string variants with rep prefix the amount of in/out
* operations per #VC exception is limited so that the kernel
* has a chance to take interrupts and re-schedule while the
* instruction is emulated.
*/
io_bytes = (exit_info_1 >> 4) & 0x7;
ghcb_count = sizeof(ghcb->shared_buffer) / io_bytes;
op_count = (exit_info_1 & IOIO_REP) ? regs->cx : 1;
exit_info_2 = min(op_count, ghcb_count);
exit_bytes = exit_info_2 * io_bytes;
es_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_ES);
/* Read bytes of OUTS into the shared buffer */
if (!(exit_info_1 & IOIO_TYPE_IN)) {
ret = vc_insn_string_read(ctxt,
(void *)(es_base + regs->si),
ghcb->shared_buffer, io_bytes,
exit_info_2, df);
if (ret)
return ret;
}
/*
* Issue an VMGEXIT to the HV to consume the bytes from the
* shared buffer or to have it write them into the shared buffer
* depending on the instruction: OUTS or INS.
*/
sw_scratch = __pa(ghcb) + offsetof(struct ghcb, shared_buffer);
ghcb_set_sw_scratch(ghcb, sw_scratch);
ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO,
exit_info_1, exit_info_2);
if (ret != ES_OK)
return ret;
/* Read bytes from shared buffer into the guest's destination. */
if (exit_info_1 & IOIO_TYPE_IN) {
ret = vc_insn_string_write(ctxt,
(void *)(es_base + regs->di),
ghcb->shared_buffer, io_bytes,
exit_info_2, df);
if (ret)
return ret;
if (df)
regs->di -= exit_bytes;
else
regs->di += exit_bytes;
} else {
if (df)
regs->si -= exit_bytes;
else
regs->si += exit_bytes;
}
if (exit_info_1 & IOIO_REP)
regs->cx -= exit_info_2;
ret = regs->cx ? ES_RETRY : ES_OK;
} else {
/* IN/OUT into/from rAX */
int bits = (exit_info_1 & 0x70) >> 1;
u64 rax = 0;
if (!(exit_info_1 & IOIO_TYPE_IN))
rax = lower_bits(regs->ax, bits);
ghcb_set_rax(ghcb, rax);
ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, exit_info_1, 0);
if (ret != ES_OK)
return ret;
if (exit_info_1 & IOIO_TYPE_IN) {
if (!ghcb_rax_is_valid(ghcb))
return ES_VMM_ERROR;
regs->ax = lower_bits(ghcb->save.rax, bits);
}
}
return ret;
}
static int vc_handle_cpuid_snp(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
{
struct pt_regs *regs = ctxt->regs;
struct cpuid_leaf leaf;
int ret;
leaf.fn = regs->ax;
leaf.subfn = regs->cx;
ret = snp_cpuid(ghcb, ctxt, &leaf);
if (!ret) {
regs->ax = leaf.eax;
regs->bx = leaf.ebx;
regs->cx = leaf.ecx;
regs->dx = leaf.edx;
}
return ret;
}
static enum es_result vc_handle_cpuid(struct ghcb *ghcb,
struct es_em_ctxt *ctxt)
{
struct pt_regs *regs = ctxt->regs;
u32 cr4 = native_read_cr4();
enum es_result ret;
int snp_cpuid_ret;
snp_cpuid_ret = vc_handle_cpuid_snp(ghcb, ctxt);
if (!snp_cpuid_ret)
return ES_OK;
if (snp_cpuid_ret != -EOPNOTSUPP)
return ES_VMM_ERROR;
ghcb_set_rax(ghcb, regs->ax);
ghcb_set_rcx(ghcb, regs->cx);
if (cr4 & X86_CR4_OSXSAVE)
/* Safe to read xcr0 */
ghcb_set_xcr0(ghcb, xgetbv(XCR_XFEATURE_ENABLED_MASK));
else
/* xgetbv will cause #GP - use reset value for xcr0 */
ghcb_set_xcr0(ghcb, 1);
ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0);
if (ret != ES_OK)
return ret;
if (!(ghcb_rax_is_valid(ghcb) &&
ghcb_rbx_is_valid(ghcb) &&
ghcb_rcx_is_valid(ghcb) &&
ghcb_rdx_is_valid(ghcb)))
return ES_VMM_ERROR;
regs->ax = ghcb->save.rax;
regs->bx = ghcb->save.rbx;
regs->cx = ghcb->save.rcx;
regs->dx = ghcb->save.rdx;
return ES_OK;
}
static enum es_result vc_handle_rdtsc(struct ghcb *ghcb,
struct es_em_ctxt *ctxt,
unsigned long exit_code)
{
bool rdtscp = (exit_code == SVM_EXIT_RDTSCP);
enum es_result ret;
ret = sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, 0, 0);
if (ret != ES_OK)
return ret;
if (!(ghcb_rax_is_valid(ghcb) && ghcb_rdx_is_valid(ghcb) &&
(!rdtscp || ghcb_rcx_is_valid(ghcb))))
return ES_VMM_ERROR;
ctxt->regs->ax = ghcb->save.rax;
ctxt->regs->dx = ghcb->save.rdx;
if (rdtscp)
ctxt->regs->cx = ghcb->save.rcx;
return ES_OK;
}
struct cc_setup_data {
struct setup_data header;
u32 cc_blob_address;
};
/*
* Search for a Confidential Computing blob passed in as a setup_data entry
* via the Linux Boot Protocol.
*/
static struct cc_blob_sev_info *find_cc_blob_setup_data(struct boot_params *bp)
{
struct cc_setup_data *sd = NULL;
struct setup_data *hdr;
hdr = (struct setup_data *)bp->hdr.setup_data;
while (hdr) {
if (hdr->type == SETUP_CC_BLOB) {
sd = (struct cc_setup_data *)hdr;
return (struct cc_blob_sev_info *)(unsigned long)sd->cc_blob_address;
}
hdr = (struct setup_data *)hdr->next;
}
return NULL;
}
/*
* Initialize the kernel's copy of the SNP CPUID table, and set up the
* pointer that will be used to access it.
*
* Maintaining a direct mapping of the SNP CPUID table used by firmware would
* be possible as an alternative, but the approach is brittle since the
* mapping needs to be updated in sync with all the changes to virtual memory
* layout and related mapping facilities throughout the boot process.
*/
static void __init setup_cpuid_table(const struct cc_blob_sev_info *cc_info)
{
const struct snp_cpuid_table *cpuid_table_fw, *cpuid_table;
int i;
if (!cc_info || !cc_info->cpuid_phys || cc_info->cpuid_len < PAGE_SIZE)
sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID);
cpuid_table_fw = (const struct snp_cpuid_table *)cc_info->cpuid_phys;
if (!cpuid_table_fw->count || cpuid_table_fw->count > SNP_CPUID_COUNT_MAX)
sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID);
cpuid_table = snp_cpuid_get_table();
memcpy((void *)cpuid_table, cpuid_table_fw, sizeof(*cpuid_table));
/* Initialize CPUID ranges for range-checking. */
for (i = 0; i < cpuid_table->count; i++) {
const struct snp_cpuid_fn *fn = &cpuid_table->fn[i];
if (fn->eax_in == 0x0)
cpuid_std_range_max = fn->eax;
else if (fn->eax_in == 0x40000000)
cpuid_hyp_range_max = fn->eax;
else if (fn->eax_in == 0x80000000)
cpuid_ext_range_max = fn->eax;
}
}
static void pvalidate_pages(struct snp_psc_desc *desc)
{
struct psc_entry *e;
unsigned long vaddr;
unsigned int size;
unsigned int i;
bool validate;
int rc;
for (i = 0; i <= desc->hdr.end_entry; i++) {
e = &desc->entries[i];
vaddr = (unsigned long)pfn_to_kaddr(e->gfn);
size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K;
validate = e->operation == SNP_PAGE_STATE_PRIVATE;
rc = pvalidate(vaddr, size, validate);
if (rc == PVALIDATE_FAIL_SIZEMISMATCH && size == RMP_PG_SIZE_2M) {
unsigned long vaddr_end = vaddr + PMD_SIZE;
for (; vaddr < vaddr_end; vaddr += PAGE_SIZE) {
rc = pvalidate(vaddr, RMP_PG_SIZE_4K, validate);
if (rc)
break;
}
}
if (rc) {
WARN(1, "Failed to validate address 0x%lx ret %d", vaddr, rc);
sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE);
}
}
}
static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc)
{
int cur_entry, end_entry, ret = 0;
struct snp_psc_desc *data;
struct es_em_ctxt ctxt;
vc_ghcb_invalidate(ghcb);
/* Copy the input desc into GHCB shared buffer */
data = (struct snp_psc_desc *)ghcb->shared_buffer;
memcpy(ghcb->shared_buffer, desc, min_t(int, GHCB_SHARED_BUF_SIZE, sizeof(*desc)));
/*
* As per the GHCB specification, the hypervisor can resume the guest
* before processing all the entries. Check whether all the entries
* are processed. If not, then keep retrying. Note, the hypervisor
* will update the data memory directly to indicate the status, so
* reference the data->hdr everywhere.
*
* The strategy here is to wait for the hypervisor to change the page
* state in the RMP table before guest accesses the memory pages. If the
* page state change was not successful, then later memory access will
* result in a crash.
*/
cur_entry = data->hdr.cur_entry;
end_entry = data->hdr.end_entry;
while (data->hdr.cur_entry <= data->hdr.end_entry) {
ghcb_set_sw_scratch(ghcb, (u64)__pa(data));
/* This will advance the shared buffer data points to. */
ret = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_PSC, 0, 0);
/*
* Page State Change VMGEXIT can pass error code through
* exit_info_2.
*/
if (WARN(ret || ghcb->save.sw_exit_info_2,
"SNP: PSC failed ret=%d exit_info_2=%llx\n",
ret, ghcb->save.sw_exit_info_2)) {
ret = 1;
goto out;
}
/* Verify that reserved bit is not set */
if (WARN(data->hdr.reserved, "Reserved bit is set in the PSC header\n")) {
ret = 1;
goto out;
}
/*
* Sanity check that entry processing is not going backwards.
* This will happen only if hypervisor is tricking us.
*/
if (WARN(data->hdr.end_entry > end_entry || cur_entry > data->hdr.cur_entry,
"SNP: PSC processing going backward, end_entry %d (got %d) cur_entry %d (got %d)\n",
end_entry, data->hdr.end_entry, cur_entry, data->hdr.cur_entry)) {
ret = 1;
goto out;
}
}
out:
return ret;
}
|