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[Xen-devel] [PATCH v3 7/8] x86emul: support RDPRU



While the PM doesn't say so, this assumes that the MPERF value read this
way gets scaled similarly to its reading through RDMSR.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v3: New.

--- a/tools/libxl/libxl_cpuid.c
+++ b/tools/libxl/libxl_cpuid.c
@@ -257,6 +257,7 @@ int libxl_cpuid_parse_config(libxl_cpuid
 
         {"invtsc",       0x80000007, NA, CPUID_REG_EDX,  8,  1},
 
+        {"rdpru",        0x80000008, NA, CPUID_REG_EBX,  4,  1},
         {"wbnoinvd",     0x80000008, NA, CPUID_REG_EBX,  9,  1},
         {"ibpb",         0x80000008, NA, CPUID_REG_EBX, 12,  1},
         {"nc",           0x80000008, NA, CPUID_REG_ECX,  0,  8},
--- a/tools/misc/xen-cpuid.c
+++ b/tools/misc/xen-cpuid.c
@@ -146,6 +146,8 @@ static const char *const str_e8b[32] =
 {
     [ 0] = "clzero",
 
+    [ 4] = "rdpru",
+
     /* [ 8] */            [ 9] = "wbnoinvd",
 
     [12] = "ibpb",
--- a/tools/tests/x86_emulator/test_x86_emulator.c
+++ b/tools/tests/x86_emulator/test_x86_emulator.c
@@ -671,6 +671,13 @@ static int read_msr(
 {
     switch ( reg )
     {
+    case 0x000000e8: /* APERF */
+    case 0xc00000e8: /* APERF_RD_ONLY */
+#define APERF_LO_VALUE 0xAEAEAEAE
+#define APERF_HI_VALUE 0xEAEAEAEA
+        *val = ((uint64_t)APERF_HI_VALUE << 32) | APERF_LO_VALUE;
+        return X86EMUL_OKAY;
+
     case 0xc0000080: /* EFER */
         *val = ctxt->addr_size > 32 ? 0x500 /* LME|LMA */ : 0;
         return X86EMUL_OKAY;
@@ -2226,6 +2233,30 @@ int main(int argc, char **argv)
             goto fail;
     printf("okay\n");
 
+    printf("%-40s", "Testing rdpru...");
+    instr[0] = 0x0f; instr[1] = 0x01; instr[2] = 0xfd;
+    regs.eip = (unsigned long)&instr[0];
+    regs.ecx = 1;
+    regs.eflags = EFLAGS_ALWAYS_SET;
+    rc = x86_emulate(&ctxt, &emulops);
+    if ( (rc != X86EMUL_OKAY) ||
+         (regs.eax != APERF_LO_VALUE) || (regs.edx != APERF_HI_VALUE) ||
+         !(regs.eflags & X86_EFLAGS_CF) ||
+         (regs.eip != (unsigned long)&instr[3]) )
+        goto fail;
+    if ( ctxt.cpuid->extd.rdpru_max < 0xffff )
+    {
+        regs.eip = (unsigned long)&instr[0];
+        regs.ecx = ctxt.cpuid->extd.rdpru_max + 1;
+        regs.eflags = EFLAGS_ALWAYS_SET | X86_EFLAGS_CF;
+        rc = x86_emulate(&ctxt, &emulops);
+        if ( (rc != X86EMUL_OKAY) || regs.eax || regs.edx ||
+             (regs.eflags & X86_EFLAGS_CF) ||
+             (regs.eip != (unsigned long)&instr[3]) )
+            goto fail;
+    }
+    printf("okay\n");
+
     printf("%-40s", "Testing movq %mm3,(%ecx)...");
     if ( stack_exec && cpu_has_mmx )
     {
--- a/tools/tests/x86_emulator/x86-emulate.c
+++ b/tools/tests/x86_emulator/x86-emulate.c
@@ -79,6 +79,8 @@ bool emul_test_init(void)
     cp.feat.movdiri = true;
     cp.feat.movdir64b = true;
     cp.extd.clzero = true;
+    cp.extd.rdpru = true;
+    cp.extd.rdpru_max = 1;
 
     if ( cpu_has_xsave )
     {
@@ -151,11 +153,11 @@ int emul_test_cpuid(
     }
 
     /*
-     * The emulator doesn't itself use CLZERO, so we can always run the
+     * The emulator doesn't itself use CLZERO/RDPRU, so we can always run the
      * respective test(s).
      */
     if ( leaf == 0x80000008 )
-        res->b |= 1U << 0;
+        res->b |= (1U << 0) | (1U << 4);
 
     return X86EMUL_OKAY;
 }
--- a/xen/arch/x86/cpuid.c
+++ b/xen/arch/x86/cpuid.c
@@ -545,6 +545,11 @@ void recalculate_cpuid_policy(struct dom
 
     p->extd.maxlinaddr = p->extd.lm ? 48 : 32;
 
+    if ( p->extd.rdpru )
+        p->extd.rdpru_max = min(p->extd.rdpru_max, max->extd.rdpru_max);
+    else
+        p->extd.rdpru_max = 0;
+
     recalculate_xstate(p);
     recalculate_misc(p);
 
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1872,6 +1872,7 @@ in_protmode(
 #define vcpu_has_fma4()        (ctxt->cpuid->extd.fma4)
 #define vcpu_has_tbm()         (ctxt->cpuid->extd.tbm)
 #define vcpu_has_clzero()      (ctxt->cpuid->extd.clzero)
+#define vcpu_has_rdpru()       (ctxt->cpuid->extd.rdpru)
 #define vcpu_has_wbnoinvd()    (ctxt->cpuid->extd.wbnoinvd)
 
 #define vcpu_has_bmi1()        (ctxt->cpuid->feat.bmi1)
@@ -5670,6 +5671,52 @@ x86_emulate(
                 limit -= sizeof(zero);
             }
             break;
+
+        case 0xfd: /* rdpru */
+            vcpu_must_have(rdpru);
+
+            if ( !mode_ring0() )
+            {
+                fail_if(!ops->read_cr);
+                if ( (rc = ops->read_cr(4, &cr4, ctxt)) != X86EMUL_OKAY )
+                    goto done;
+                generate_exception_if(cr4 & X86_CR4_TSD, EXC_UD);
+            }
+
+            switch ( _regs.ecx )
+            {
+            case 0:  n = MSR_IA32_MPERF; break;
+            case 1:  n = MSR_IA32_APERF; break;
+            default: n = 0; break;
+            }
+            if ( _regs.ecx > ctxt->cpuid->extd.rdpru_max )
+                n = 0;
+
+            _regs.eflags &= ~EFLAGS_MASK;
+            if ( n )
+            {
+                fail_if(!ops->read_msr);
+                switch ( rc = ops->read_msr(n, &msr_val, ctxt) )
+                {
+                case X86EMUL_OKAY:
+                    _regs.eflags |= X86_EFLAGS_CF;
+                    break;
+
+                case X86EMUL_EXCEPTION:
+                    x86_emul_reset_event(ctxt);
+                    rc = X86EMUL_OKAY;
+                    break;
+
+                default:
+                    goto done;
+                }
+            }
+
+            if ( !(_regs.eflags & X86_EFLAGS_CF) )
+                msr_val = 0;
+            _regs.r(dx) = msr_val >> 32;
+            _regs.r(ax) = (uint32_t)msr_val;
+            break;
         }
 
 #define _GRP7(mod, reg) \
--- a/xen/include/public/arch-x86/cpufeatureset.h
+++ b/xen/include/public/arch-x86/cpufeatureset.h
@@ -246,6 +246,7 @@ XEN_CPUFEATURE(EFRO,          7*32+10) /
 
 /* AMD-defined CPU features, CPUID level 0x80000008.ebx, word 8 */
 XEN_CPUFEATURE(CLZERO,        8*32+ 0) /*A  CLZERO instruction */
+XEN_CPUFEATURE(RDPRU,         8*32+ 4) /*A  RDPRU instruction */
 XEN_CPUFEATURE(WBNOINVD,      8*32+ 9) /*   WBNOINVD instruction */
 XEN_CPUFEATURE(IBPB,          8*32+12) /*A  IBPB support only (no IBRS, used 
by AMD) */
 
--- a/xen/include/xen/lib/x86/cpuid.h
+++ b/xen/include/xen/lib/x86/cpuid.h
@@ -259,7 +259,8 @@ struct cpuid_policy
                 uint32_t e8b;
                 struct { DECL_BITFIELD(e8b); };
             };
-            uint32_t /* c */:32, /* d */:32;
+            uint32_t /* c */:32;
+            uint16_t :16, rdpru_max;
         };
     } extd;
 

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