[Xen-devel] [PATCH v3 4/8] x86emul: support INVPCID

[Jan Beulich <jbeulich@xxxxxxxx>]

Just like for INVLPGA the HVM hook only supports PCID 0 for the time
being for individual address invalidation. It also translates the other
types to a full flush, which is architecturally permitted and
performance-wise presumably not much worse because emulation is slow
anyway.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
v3: Re-base over X86_INVPCID_* name change.
v2: New.

--- a/tools/fuzz/x86_instruction_emulator/fuzz-emul.c
+++ b/tools/fuzz/x86_instruction_emulator/fuzz-emul.c
@@ -382,6 +382,7 @@ static int fuzz_tlb_op(
         assert(is_x86_user_segment(aux));
         /* fall through */
     case x86emul_invlpga:
+    case x86emul_invpcid:
         assert(ctxt->addr_size == 64 || !(addr >> 32));
         break;
     }
--- a/tools/tests/x86_emulator/test_x86_emulator.c
+++ b/tools/tests/x86_emulator/test_x86_emulator.c
@@ -684,6 +684,38 @@ static int read_msr(
     return X86EMUL_UNHANDLEABLE;
 }
 
+#define INVPCID_ADDR 0x12345678
+#define INVPCID_PCID 0x123
+
+static int read_cr_invpcid(
+    unsigned int reg,
+    unsigned long *val,
+    struct x86_emulate_ctxt *ctxt)
+{
+    int rc = emul_test_read_cr(reg, val, ctxt);
+
+    if ( rc == X86EMUL_OKAY && reg == 4 )
+        *val |= X86_CR4_PCIDE;
+
+    return rc;
+}
+
+static int tlb_op_invpcid(
+    enum x86emul_tlb_op op,
+    unsigned long addr,
+    unsigned long aux,
+    struct x86_emulate_ctxt *ctxt)
+{
+    static unsigned int seq;
+
+    if ( op != x86emul_invpcid || addr != INVPCID_ADDR ||
+         x86emul_invpcid_pcid(aux) != (seq < 4 ? 0 : INVPCID_PCID) ||
+         x86emul_invpcid_type(aux) != (seq++ & 3) )
+        return X86EMUL_UNHANDLEABLE;
+
+    return X86EMUL_OKAY;
+}
+
 static struct x86_emulate_ops emulops = {
     .read       = read,
     .insn_fetch = fetch,
@@ -4482,6 +4514,46 @@ int main(int argc, char **argv)
         printf("okay\n");
     }
     else
+        printf("skipped\n");
+
+    printf("%-40s", "Testing invpcid 16(%ecx),%%edx...");
+    if ( stack_exec )
+    {
+        decl_insn(invpcid);
+
+        asm volatile ( put_insn(invpcid, "invpcid 16(%0), %1")
+                       :: "c" (NULL), "d" (0L) );
+
+        res[4] = 0;
+        res[5] = 0;
+        res[6] = INVPCID_ADDR;
+        res[7] = 0;
+        regs.ecx = (unsigned long)res;
+        emulops.tlb_op = tlb_op_invpcid;
+
+        for ( ; ; )
+        {
+            for ( regs.edx = 0; regs.edx < 4; ++regs.edx )
+            {
+                set_insn(invpcid);
+                rc = x86_emulate(&ctxt, &emulops);
+                if ( rc != X86EMUL_OKAY || !check_eip(invpcid) )
+                    goto fail;
+            }
+
+            if ( ctxt.addr_size < 64 || res[4] == INVPCID_PCID )
+                break;
+
+            emulops.read_cr = read_cr_invpcid;
+            res[4] = INVPCID_PCID;
+        }
+
+        emulops.read_cr = emul_test_read_cr;
+        emulops.tlb_op = NULL;
+
+        printf("okay\n");
+    }
+    else
         printf("skipped\n");
 
 #undef decl_insn
--- a/tools/tests/x86_emulator/x86-emulate.c
+++ b/tools/tests/x86_emulator/x86-emulate.c
@@ -72,6 +72,7 @@ bool emul_test_init(void)
      * them.
      */
     cp.basic.movbe = true;
+    cp.feat.invpcid = true;
     cp.feat.adx = true;
     cp.feat.avx512pf = cp.feat.avx512f;
     cp.feat.rdpid = true;
@@ -141,7 +142,7 @@ int emul_test_cpuid(
      */
     if ( leaf == 7 && subleaf == 0 )
     {
-        res->b |= 1U << 19;
+        res->b |= (1U << 10) | (1U << 19);
         if ( res->b & (1U << 16) )
             res->b |= 1U << 26;
         res->c |= 1U << 22;
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2390,8 +2390,16 @@ static int hvmemul_tlb_op(
             paging_invlpg(current, addr);
         break;
 
+    case x86emul_invpcid:
+        if ( x86emul_invpcid_type(aux) != X86_INVPCID_INDIV_ADDR )
+        {
+            hvm_asid_flush_vcpu(current);
+            break;
+        }
+        aux = x86emul_invpcid_pcid(aux);
+        /* fall through */
     case x86emul_invlpga:
-        /* TODO: Support ASIDs. */
+        /* TODO: Support ASIDs/PCIDs. */
         if ( !aux )
             paging_invlpg(current, addr);
         else
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -496,6 +496,7 @@ static const struct ext0f38_table {
     [0x7a ... 0x7c] = { .simd_size = simd_none, .two_op = 1 },
     [0x7d ... 0x7e] = { .simd_size = simd_packed_int, .d8s = d8s_vl },
     [0x7f] = { .simd_size = simd_packed_fp, .d8s = d8s_vl },
+    [0x82] = { .simd_size = simd_other },
     [0x83] = { .simd_size = simd_packed_int, .d8s = d8s_vl },
     [0x88] = { .simd_size = simd_packed_fp, .two_op = 1, .d8s = d8s_dq },
     [0x89] = { .simd_size = simd_packed_int, .two_op = 1, .d8s = d8s_dq },
@@ -1875,6 +1876,7 @@ in_protmode(
 #define vcpu_has_hle()         (ctxt->cpuid->feat.hle)
 #define vcpu_has_avx2()        (ctxt->cpuid->feat.avx2)
 #define vcpu_has_bmi2()        (ctxt->cpuid->feat.bmi2)
+#define vcpu_has_invpcid()     (ctxt->cpuid->feat.invpcid)
 #define vcpu_has_rtm()         (ctxt->cpuid->feat.rtm)
 #define vcpu_has_mpx()         (ctxt->cpuid->feat.mpx)
 #define vcpu_has_avx512f()     (ctxt->cpuid->feat.avx512f)
@@ -9124,6 +9126,48 @@ x86_emulate(
         ASSERT(!state->simd_size);
         break;
 
+    case X86EMUL_OPC_66(0x0f38, 0x82): /* invpcid reg,m128 */
+        vcpu_must_have(invpcid);
+        generate_exception_if(ea.type != OP_MEM, EXC_UD);
+        generate_exception_if(!mode_ring0(), EXC_GP, 0);
+
+        if ( (rc = ops->read(ea.mem.seg, ea.mem.off, mmvalp, 16,
+                             ctxt)) != X86EMUL_OKAY )
+            goto done;
+
+        generate_exception_if(mmvalp->xmm[0] & ~0xfff, EXC_GP, 0);
+        dst.val = mode_64bit() ? *dst.reg : (uint32_t)*dst.reg;
+
+        switch ( dst.val )
+        {
+        case X86_INVPCID_INDIV_ADDR:
+             generate_exception_if(!is_canonical_address(mmvalp->xmm[1]),
+                                   EXC_GP, 0);
+             /* fall through */
+        case X86_INVPCID_SINGLE_CTXT:
+             if ( !mode_64bit() || !ops->read_cr )
+                 cr4 = 0;
+             else if ( (rc = ops->read_cr(4, &cr4, ctxt)) != X86EMUL_OKAY )
+                 goto done;
+             generate_exception_if(!(cr4 & X86_CR4_PCIDE) && mmvalp->xmm[0],
+                                   EXC_GP, 0);
+             break;
+        case X86_INVPCID_ALL_INCL_GLOBAL:
+        case X86_INVPCID_ALL_NON_GLOBAL:
+             break;
+        default:
+             generate_exception(EXC_GP, 0);
+        }
+
+        fail_if(!ops->tlb_op);
+        if ( (rc = ops->tlb_op(x86emul_invpcid, truncate_ea(mmvalp->xmm[1]),
+                               x86emul_invpcid_aux(mmvalp->xmm[0], dst.val),
+                               ctxt)) != X86EMUL_OKAY )
+            goto done;
+
+        state->simd_size = simd_none;
+        break;
+
     case X86EMUL_OPC_EVEX_66(0x0f38, 0x83): /* vpmultishiftqb 
[xyz]mm/mem,[xyz]mm,[xyz]mm{k} */
         generate_exception_if(!evex.w, EXC_UD);
         host_and_vcpu_must_have(avx512_vbmi);
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -188,8 +188,26 @@ enum x86emul_cache_op {
 enum x86emul_tlb_op {
     x86emul_invlpg,
     x86emul_invlpga,
+    x86emul_invpcid,
 };
 
+static inline unsigned int x86emul_invpcid_aux(unsigned int pcid,
+                                            unsigned int type)
+{
+    ASSERT(!(pcid & ~0xfff));
+    return (type << 12) | pcid;
+}
+
+static inline unsigned int x86emul_invpcid_pcid(unsigned int aux)
+{
+    return aux & 0xfff;
+}
+
+static inline unsigned int x86emul_invpcid_type(unsigned int aux)
+{
+    return aux >> 12;
+}
+
 struct x86_emulate_state;
 
 /*
@@ -483,6 +501,8 @@ struct x86_emulate_ops
      * @addr and @aux have @op-specific meaning:
      * - INVLPG:  @aux:@addr represent seg:offset
      * - INVLPGA: @addr is the linear address, @aux the ASID
+     * - INVPCID: @addr is the linear address, @aux the combination of
+     *            PCID and type (see x86emul_invpcid_*()).
      */
     int (*tlb_op)(
         enum x86emul_tlb_op op,


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