[PATCH v7 08/10] x86/sev-es: Use insn_decode_mmio() for MMIO implementation

Kuppuswamy Sathyanarayanan
2021-10-05T20:42:24Z

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

Switch SEV implementation to insn_decode_mmio(). The helper is going
to be used by TDX too.

No functional changes. It is only build-tested.

Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---

Changes since v6:
* None

Changes since v5:
* None

Changes since v4:
* None

Changes since v3:
* None

Changes since v2:
* None

arch/x86/kernel/sev.c | 171 ++++++++++--------------------------------
1 file changed, 40 insertions(+), 131 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 53a6837d354b..e2f1ae006114 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -807,22 +807,6 @@ static void __init vc_early_forward_exception(struct es_em_ctxt *ctxt)
do_early_exception(ctxt->regs, trapnr);
}

-static long *vc_insn_get_reg(struct es_em_ctxt *ctxt)
-{
- long *reg_array;
- int offset;
-
- reg_array = (long *)ctxt->regs;
- offset = insn_get_modrm_reg_off(&ctxt->insn, ctxt->regs);
-
- if (offset < 0)
- return NULL;
-
- offset /= sizeof(long);
-
- return reg_array + offset;
-}
-
static long *vc_insn_get_rm(struct es_em_ctxt *ctxt)
{
long *reg_array;
@@ -870,76 +854,6 @@ static enum es_result vc_do_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
return sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, exit_info_1, exit_info_2);
}

-static enum es_result vc_handle_mmio_twobyte_ops(struct ghcb *ghcb,
- struct es_em_ctxt *ctxt)
-{
- struct insn *insn = &ctxt->insn;
- unsigned int bytes = 0;
- enum es_result ret;
- int sign_byte;
- long *reg_data;
-
- switch (insn->opcode.bytes[1]) {
- /* MMIO Read w/ zero-extension */
- case 0xb6:
- bytes = 1;
- fallthrough;
- case 0xb7:
- if (!bytes)
- bytes = 2;
-
- ret = vc_do_mmio(ghcb, ctxt, bytes, true);
- if (ret)
- break;
-
- /* Zero extend based on operand size */
- reg_data = vc_insn_get_reg(ctxt);
- if (!reg_data)
- return ES_DECODE_FAILED;
-
- memset(reg_data, 0, insn->opnd_bytes);
-
- memcpy(reg_data, ghcb->shared_buffer, bytes);
- break;
-
- /* MMIO Read w/ sign-extension */
- case 0xbe:
- bytes = 1;
- fallthrough;
- case 0xbf:
- if (!bytes)
- bytes = 2;
-
- ret = vc_do_mmio(ghcb, ctxt, bytes, true);
- if (ret)
- break;
-
- /* Sign extend based on operand size */
- reg_data = vc_insn_get_reg(ctxt);
- if (!reg_data)
- return ES_DECODE_FAILED;
-
- if (bytes == 1) {
- u8 *val = (u8 *)ghcb->shared_buffer;
-
- sign_byte = (*val & 0x80) ? 0xff : 0x00;
- } else {
- u16 *val = (u16 *)ghcb->shared_buffer;
-
- sign_byte = (*val & 0x8000) ? 0xff : 0x00;
- }
- memset(reg_data, sign_byte, insn->opnd_bytes);
-
- memcpy(reg_data, ghcb->shared_buffer, bytes);
- break;
-
- default:
- ret = ES_UNSUPPORTED;
- }
-
- return ret;
-}
-
/*
* The MOVS instruction has two memory operands, which raises the
* problem that it is not known whether the access to the source or the
@@ -1007,83 +921,78 @@ static enum es_result vc_handle_mmio_movs(struct es_em_ctxt *ctxt,
return ES_RETRY;
}

-static enum es_result vc_handle_mmio(struct ghcb *ghcb,
- struct es_em_ctxt *ctxt)
+static enum es_result vc_handle_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
{
struct insn *insn = &ctxt->insn;
unsigned int bytes = 0;
+ enum mmio_type mmio;
enum es_result ret;
+ u8 sign_byte;
long *reg_data;

- switch (insn->opcode.bytes[0]) {
- /* MMIO Write */
- case 0x88:
- bytes = 1;
- fallthrough;
- case 0x89:
- if (!bytes)
- bytes = insn->opnd_bytes;
+ mmio = insn_decode_mmio(insn, &bytes);
+ if (mmio == MMIO_DECODE_FAILED)
+ return ES_DECODE_FAILED;

- reg_data = vc_insn_get_reg(ctxt);
+ if (mmio != MMIO_WRITE_IMM && mmio != MMIO_MOVS) {
+ reg_data = insn_get_modrm_reg_ptr(insn, ctxt->regs);
if (!reg_data)
return ES_DECODE_FAILED;
+ }

+ switch (mmio) {
+ case MMIO_WRITE:
memcpy(ghcb->shared_buffer, reg_data, bytes);
-
ret = vc_do_mmio(ghcb, ctxt, bytes, false);
break;
-
- case 0xc6:
- bytes = 1;
- fallthrough;
- case 0xc7:
- if (!bytes)
- bytes = insn->opnd_bytes;
-
+ case MMIO_WRITE_IMM:
memcpy(ghcb->shared_buffer, insn->immediate1.bytes, bytes);
-
ret = vc_do_mmio(ghcb, ctxt, bytes, false);
break;
-
- /* MMIO Read */
- case 0x8a:
- bytes = 1;
- fallthrough;
- case 0x8b:
- if (!bytes)
- bytes = insn->opnd_bytes;
-
+ case MMIO_READ:
ret = vc_do_mmio(ghcb, ctxt, bytes, true);
if (ret)
break;

- reg_data = vc_insn_get_reg(ctxt);
- if (!reg_data)
- return ES_DECODE_FAILED;
-
/* Zero-extend for 32-bit operation */
if (bytes == 4)
*reg_data = 0;

memcpy(reg_data, ghcb->shared_buffer, bytes);
break;
+ case MMIO_READ_ZERO_EXTEND:
+ ret = vc_do_mmio(ghcb, ctxt, bytes, true);
+ if (ret)
+ break;
+
+ memset(reg_data, 0, insn->opnd_bytes);
+ memcpy(reg_data, ghcb->shared_buffer, bytes);
+ break;
+ case MMIO_READ_SIGN_EXTEND:
+ ret = vc_do_mmio(ghcb, ctxt, bytes, true);
+ if (ret)
+ break;

- /* MOVS instruction */
- case 0xa4:
- bytes = 1;
- fallthrough;
- case 0xa5:
- if (!bytes)
- bytes = insn->opnd_bytes;
+ if (bytes == 1) {
+ u8 *val = (u8 *)ghcb->shared_buffer;

- ret = vc_handle_mmio_movs(ctxt, bytes);
+ sign_byte = (*val & 0x80) ? 0xff : 0x00;
+ } else {
+ u16 *val = (u16 *)ghcb->shared_buffer;
+
+ sign_byte = (*val & 0x8000) ? 0xff : 0x00;
+ }
+
+ /* Sign extend based on operand size */
+ memset(reg_data, sign_byte, insn->opnd_bytes);
+ memcpy(reg_data, ghcb->shared_buffer, bytes);
break;
- /* Two-Byte Opcodes */
- case 0x0f:
- ret = vc_handle_mmio_twobyte_ops(ghcb, ctxt);
+ case MMIO_MOVS:
+ ret = vc_handle_mmio_movs(ctxt, bytes);
break;
default:
ret = ES_UNSUPPORTED;
+ break;
}

return ret;
--
2.25.1