[RFC PATCH 15/31] KVM: selftests: Add instruction decoding for movabs instructions

[Neeraj Upadhyay]

Certain xapic MMIO reads and writes get compiled into movabs
instruction which uses rax as the register containing data and
8-byte address encoded as part of the instruction. Add support
to decode these instructions.

Signed-off-by: Neeraj Upadhyay <neeraj.upadh...@amd.com>
---
 .../testing/selftests/kvm/lib/x86/insn-eval.c |  8 +++++
 tools/testing/selftests/kvm/lib/x86/sev.c     | 35 ++++++++++++++-----
 2 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/x86/insn-eval.c 
b/tools/testing/selftests/kvm/lib/x86/insn-eval.c
index efa4d3fde504..60c8c7cf5658 100644
--- a/tools/testing/selftests/kvm/lib/x86/insn-eval.c
+++ b/tools/testing/selftests/kvm/lib/x86/insn-eval.c
@@ -1712,6 +1712,14 @@ enum insn_mmio_type insn_decode_mmio(struct insn *insn, 
int *bytes)
                        break;
                }
                break;
+       case 0xa1:
+               type = INSN_MMIO_READ_MOV_ABS;
+               *bytes = insn->opnd_bytes;
+               break;
+       case 0xa3:
+               type = INSN_MMIO_WRITE_MOV_ABS;
+               *bytes = insn->opnd_bytes;
+               break;
        }
 
        return type;
diff --git a/tools/testing/selftests/kvm/lib/x86/sev.c 
b/tools/testing/selftests/kvm/lib/x86/sev.c
index 16d6b21649d1..24aaa75ec450 100644
--- a/tools/testing/selftests/kvm/lib/x86/sev.c
+++ b/tools/testing/selftests/kvm/lib/x86/sev.c
@@ -517,9 +517,11 @@ void sev_es_pv_mmio_rw(uint32_t *reg_gpa, uint32_t *data, 
bool write)
 }
 
 static void do_mmio(struct ghcb_entry *entry, struct ex_regs *regs,
-               struct insn *insn, unsigned int bytes, bool read)
+               struct insn *insn, unsigned int bytes, bool read,
+               void *ref)
 {
-       void *ref = insn_get_addr_ref(insn, regs);
+       if (!ref)
+               ref = insn_get_addr_ref(insn, regs);
 
        register_ghcb_page(entry->gpa);
        __sev_es_hv_mmio_rw(entry, ref, bytes, !read);
@@ -648,11 +650,12 @@ static void sev_es_vc_mmio_handler(struct ex_regs *regs)
        char buffer[MAX_INSN_SIZE];
        struct ghcb_entry *entry;
        enum insn_mmio_type mmio;
-       unsigned long *reg_data;
+       unsigned long *reg_data = NULL;
        unsigned int bytes;
        struct ghcb *ghcb;
        uint8_t sign_byte;
        struct insn insn;
+       void *abs_ref;
        int ret;
 
        memcpy(buffer, (uint8_t *)regs->rip, MAX_INSN_SIZE);
@@ -664,7 +667,9 @@ static void sev_es_vc_mmio_handler(struct ex_regs *regs)
        mmio = insn_decode_mmio(&insn, (int *)&bytes);
        __GUEST_ASSERT(!(mmio == INSN_MMIO_DECODE_FAILED), " MMIO decode 
failed\n");
 
-       if (mmio != INSN_MMIO_WRITE_IMM && mmio != INSN_MMIO_MOVS) {
+       if (mmio == INSN_MMIO_WRITE_MOV_ABS || mmio == INSN_MMIO_READ_MOV_ABS) {
+               reg_data = &regs->rax;
+       } else if (mmio != INSN_MMIO_WRITE_IMM && mmio != INSN_MMIO_MOVS) {
                reg_data = insn_get_modrm_reg_ptr(&insn, regs);
                __GUEST_ASSERT(reg_data, "insn_get_modrm_reg_ptr failed\n");
        }
@@ -675,25 +680,37 @@ static void sev_es_vc_mmio_handler(struct ex_regs *regs)
        switch (mmio) {
        case INSN_MMIO_WRITE:
                memcpy(ghcb->shared_buffer, reg_data, bytes);
-               do_mmio(entry, regs, &insn, bytes, false);
+               do_mmio(entry, regs, &insn, bytes, false, NULL);
                break;
        case INSN_MMIO_WRITE_IMM:
                memcpy(ghcb->shared_buffer, insn.immediate1.bytes, bytes);
-               do_mmio(entry, regs, &insn, bytes, false);
+               do_mmio(entry, regs, &insn, bytes, false, NULL);
+               break;
+       case INSN_MMIO_WRITE_MOV_ABS:
+               abs_ref = (void *)*(uint64_t *)((uint8_t *)regs->rip + 1);
+               memcpy(ghcb->shared_buffer, reg_data, bytes);
+               do_mmio(entry, regs, &insn, bytes, false, abs_ref);
                break;
        case INSN_MMIO_READ:
-               do_mmio(entry, regs, &insn, bytes, true);
+               do_mmio(entry, regs, &insn, bytes, true, NULL);
+               if (bytes == 4)
+                       *reg_data = 0;
+               memcpy(reg_data, ghcb->shared_buffer, bytes);
+               break;
+       case INSN_MMIO_READ_MOV_ABS:
+               abs_ref = (void *)*(uint64_t *)((char *)regs->rip + 1);
+               do_mmio(entry, regs, &insn, bytes, true, abs_ref);
                if (bytes == 4)
                        *reg_data = 0;
                memcpy(reg_data, ghcb->shared_buffer, bytes);
                break;
        case INSN_MMIO_READ_ZERO_EXTEND:
-               do_mmio(entry, regs, &insn, bytes, true);
+               do_mmio(entry, regs, &insn, bytes, true, NULL);
                memset(reg_data, 0, insn.opnd_bytes);
                memcpy(reg_data, ghcb->shared_buffer, bytes);
                break;
        case INSN_MMIO_READ_SIGN_EXTEND:
-               do_mmio(entry, regs, &insn, bytes, true);
+               do_mmio(entry, regs, &insn, bytes, true, NULL);
                if (bytes == 1) {
                        uint8_t *val = (uint8_t *)ghcb->shared_buffer;
 
-- 
2.34.1