target-arm: Add raw_readfn and raw_writefn to ARMCPRegInfo

For reading and writing register values from the kernel for KVM,
we need to provide accessor functions which are guaranteed to succeed
and don't impose access checks, mask out unwritable bits, etc.
Define new fields raw_readfn and raw_writefn for this purpose;
these only need to be provided if there is a readfn or writefn
already and it is not suitable.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 72 insertions, 27 deletions

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 00b664a0f8..453f5f81d0 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -447,12 +447,15 @@ void armv7m_nvic_complete_irq(void *opaque, int irq);
  * a register definition to override a previous definition for the
  * same (cp, is64, crn, crm, opc1, opc2) tuple: either the new or the
  * old must have the OVERRIDE bit set.
+ * NO_MIGRATE indicates that this register should be ignored for migration;
+ * (eg because any state is accessed via some other coprocessor register).
  */
 #define ARM_CP_SPECIAL 1
 #define ARM_CP_CONST 2
 #define ARM_CP_64BIT 4
 #define ARM_CP_SUPPRESS_TB_END 8
 #define ARM_CP_OVERRIDE 16
+#define ARM_CP_NO_MIGRATE 32
 #define ARM_CP_NOP (ARM_CP_SPECIAL | (1 << 8))
 #define ARM_CP_WFI (ARM_CP_SPECIAL | (2 << 8))
 #define ARM_LAST_SPECIAL ARM_CP_WFI
@@ -575,6 +578,19 @@ struct ARMCPRegInfo {
      * by fieldoffset.
      */
     CPWriteFn *writefn;
+    /* Function for doing a "raw" read; used when we need to copy
+     * coprocessor state to the kernel for KVM or out for
+     * migration. This only needs to be provided if there is also a
+     * readfn and it makes an access permission check.
+     */
+    CPReadfn *raw_readfn;
+    /* Function for doing a "raw" write; used when we need to copy KVM
+     * kernel coprocessor state into userspace, or for inbound
+     * migration. This only needs to be provided if there is also a
+     * readfn and it makes an access permission check or masks out
+     * "unwritable" bits.
+     */
+    CPWritefn *raw_writefn;
     /* Function for resetting the register. If NULL, then reset will be done
      * by writing resetvalue to the field specified in fieldoffset. If
      * fieldoffset is 0 then no reset will be done.
diff --git a/target-arm/helper.c b/target-arm/helper.c
index f2cc63002f..3db824f50a 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -155,13 +155,17 @@ static const ARMCPRegInfo cp_reginfo[] = {
      * the unified TLB ops but also the dside/iside/inner-shareable variants.
      */
     { .name = "TLBIALL", .cp = 15, .crn = 8, .crm = CP_ANY,
-      .opc1 = CP_ANY, .opc2 = 0, .access = PL1_W, .writefn = tlbiall_write, },
+      .opc1 = CP_ANY, .opc2 = 0, .access = PL1_W, .writefn = tlbiall_write,
+      .type = ARM_CP_NO_MIGRATE },
     { .name = "TLBIMVA", .cp = 15, .crn = 8, .crm = CP_ANY,
-      .opc1 = CP_ANY, .opc2 = 1, .access = PL1_W, .writefn = tlbimva_write, },
+      .opc1 = CP_ANY, .opc2 = 1, .access = PL1_W, .writefn = tlbimva_write,
+      .type = ARM_CP_NO_MIGRATE },
     { .name = "TLBIASID", .cp = 15, .crn = 8, .crm = CP_ANY,
-      .opc1 = CP_ANY, .opc2 = 2, .access = PL1_W, .writefn = tlbiasid_write, },
+      .opc1 = CP_ANY, .opc2 = 2, .access = PL1_W, .writefn = tlbiasid_write,
+      .type = ARM_CP_NO_MIGRATE },
     { .name = "TLBIMVAA", .cp = 15, .crn = 8, .crm = CP_ANY,
-      .opc1 = CP_ANY, .opc2 = 3, .access = PL1_W, .writefn = tlbimvaa_write, },
+      .opc1 = CP_ANY, .opc2 = 3, .access = PL1_W, .writefn = tlbimvaa_write,
+      .type = ARM_CP_NO_MIGRATE },
     /* Cache maintenance ops; some of this space may be overridden later. */
     { .name = "CACHEMAINT", .cp = 15, .crn = 7, .crm = CP_ANY,
       .opc1 = 0, .opc2 = CP_ANY, .access = PL1_W,
@@ -196,7 +200,8 @@ static const ARMCPRegInfo not_v7_cp_reginfo[] = {
       .resetvalue = 0 },
     /* v6 doesn't have the cache ID registers but Linux reads them anyway */
     { .name = "DUMMY", .cp = 15, .crn = 0, .crm = 0, .opc1 = 1, .opc2 = CP_ANY,
-      .access = PL1_R, .type = ARM_CP_CONST, .resetvalue = 0 },
+      .access = PL1_R, .type = ARM_CP_CONST | ARM_CP_NO_MIGRATE,
+      .resetvalue = 0 },
     REGINFO_SENTINEL
 };
 
@@ -235,6 +240,21 @@ static const ARMCPRegInfo v6_cp_reginfo[] = {
     REGINFO_SENTINEL
 };
 
+
+static int raw_read(CPUARMState *env, const ARMCPRegInfo *ri,
+                    uint64_t *value)
+{
+    *value = CPREG_FIELD32(env, ri);
+    return 0;
+}
+
+static int raw_write(CPUARMState *env, const ARMCPRegInfo *ri,
+                     uint64_t value)
+{
+    CPREG_FIELD32(env, ri) = value;
+    return 0;
+}
+
 static int pmreg_read(CPUARMState *env, const ARMCPRegInfo *ri,
                       uint64_t *value)
 {
@@ -366,13 +386,16 @@ static const ARMCPRegInfo v7_cp_reginfo[] = {
     { .name = "PMCNTENSET", .cp = 15, .crn = 9, .crm = 12, .opc1 = 0, .opc2 = 1,
       .access = PL0_RW, .resetvalue = 0,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pmcnten),
-      .readfn = pmreg_read, .writefn = pmcntenset_write },
+      .readfn = pmreg_read, .writefn = pmcntenset_write,
+      .raw_readfn = raw_read, .raw_writefn = raw_write },
     { .name = "PMCNTENCLR", .cp = 15, .crn = 9, .crm = 12, .opc1 = 0, .opc2 = 2,
       .access = PL0_RW, .fieldoffset = offsetof(CPUARMState, cp15.c9_pmcnten),
-      .readfn = pmreg_read, .writefn = pmcntenclr_write },
+      .readfn = pmreg_read, .writefn = pmcntenclr_write,
+      .type = ARM_CP_NO_MIGRATE },
     { .name = "PMOVSR", .cp = 15, .crn = 9, .crm = 12, .opc1 = 0, .opc2 = 3,
       .access = PL0_RW, .fieldoffset = offsetof(CPUARMState, cp15.c9_pmovsr),
-      .readfn = pmreg_read, .writefn = pmovsr_write },
+      .readfn = pmreg_read, .writefn = pmovsr_write,
+      .raw_readfn = raw_read, .raw_writefn = raw_write },
     /* Unimplemented so WI. Strictly speaking write accesses in PL0 should
      * respect PMUSERENR.
      */
@@ -389,7 +412,8 @@ static const ARMCPRegInfo v7_cp_reginfo[] = {
     { .name = "PMXEVTYPER", .cp = 15, .crn = 9, .crm = 13, .opc1 = 0, .opc2 = 1,
       .access = PL0_RW,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pmxevtyper),
-      .readfn = pmreg_read, .writefn = pmxevtyper_write },
+      .readfn = pmreg_read, .writefn = pmxevtyper_write,
+      .raw_readfn = raw_read, .raw_writefn = raw_write },
     /* Unimplemented, RAZ/WI. XXX PMUSERENR */
     { .name = "PMXEVCNTR", .cp = 15, .crn = 9, .crm = 13, .opc1 = 0, .opc2 = 2,
       .access = PL0_RW, .type = ARM_CP_CONST, .resetvalue = 0 },
@@ -397,22 +421,22 @@ static const ARMCPRegInfo v7_cp_reginfo[] = {
       .access = PL0_R | PL1_RW,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pmuserenr),
       .resetvalue = 0,
-      .writefn = pmuserenr_write },
+      .writefn = pmuserenr_write, .raw_writefn = raw_write },
     { .name = "PMINTENSET", .cp = 15, .crn = 9, .crm = 14, .opc1 = 0, .opc2 = 1,
       .access = PL1_RW,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pminten),
       .resetvalue = 0,
-      .writefn = pmintenset_write },
+      .writefn = pmintenset_write, .raw_writefn = raw_write },
     { .name = "PMINTENCLR", .cp = 15, .crn = 9, .crm = 14, .opc1 = 0, .opc2 = 2,
-      .access = PL1_RW,
+      .access = PL1_RW, .type = ARM_CP_NO_MIGRATE,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pminten),
-      .resetvalue = 0,
-      .writefn = pmintenclr_write },
+      .resetvalue = 0, .writefn = pmintenclr_write, },
     { .name = "SCR", .cp = 15, .crn = 1, .crm = 1, .opc1 = 0, .opc2 = 0,
       .access = PL1_RW, .fieldoffset = offsetof(CPUARMState, cp15.c1_scr),
       .resetvalue = 0, },
+    // XXX add the ersatz register encodings for migrating CCSIDR state
     { .name = "CCSIDR", .cp = 15, .crn = 0, .crm = 0, .opc1 = 1, .opc2 = 0,
-      .access = PL1_R, .readfn = ccsidr_read },
+      .access = PL1_R, .readfn = ccsidr_read, .type = ARM_CP_NO_MIGRATE },
     { .name = "CSSELR", .cp = 15, .crn = 0, .crm = 0, .opc1 = 2, .opc2 = 0,
       .access = PL1_RW, .fieldoffset = offsetof(CPUARMState, cp15.c0_cssel),
       .writefn = csselr_write, .resetvalue = 0 },
@@ -461,7 +485,7 @@ static const ARMCPRegInfo t2ee_cp_reginfo[] = {
       .writefn = teecr_write },
     { .name = "TEEHBR", .cp = 14, .crn = 1, .crm = 0, .opc1 = 6, .opc2 = 0,
       .access = PL0_RW, .fieldoffset = offsetof(CPUARMState, teehbr),
-      .resetvalue = 0,
+      .resetvalue = 0, .raw_readfn = raw_read, .raw_writefn = raw_write,
       .readfn = teehbr_read, .writefn = teehbr_write },
     REGINFO_SENTINEL
 };
@@ -486,7 +510,8 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
     /* Dummy implementation: RAZ/WI the whole crn=14 space */
     { .name = "GENERIC_TIMER", .cp = 15, .crn = 14,
       .crm = CP_ANY, .opc1 = CP_ANY, .opc2 = CP_ANY,
-      .access = PL1_RW, .type = ARM_CP_CONST, .resetvalue = 0 },
+      .access = PL1_RW, .type = ARM_CP_CONST | ARM_CP_NO_MIGRATE,
+      .resetvalue = 0 },
     REGINFO_SENTINEL
 };
 
@@ -579,7 +604,7 @@ static const ARMCPRegInfo vapa_cp_reginfo[] = {
       .writefn = par_write },
 #ifndef CONFIG_USER_ONLY
     { .name = "ATS", .cp = 15, .crn = 7, .crm = 8, .opc1 = 0, .opc2 = CP_ANY,
-      .access = PL1_W, .writefn = ats_write },
+      .access = PL1_W, .writefn = ats_write, .type = ARM_CP_NO_MIGRATE },
 #endif
     REGINFO_SENTINEL
 };
@@ -664,11 +689,11 @@ static int arm946_prbs_write(CPUARMState *env, const ARMCPRegInfo *ri,
 
 static const ARMCPRegInfo pmsav5_cp_reginfo[] = {
     { .name = "DATA_AP", .cp = 15, .crn = 5, .crm = 0, .opc1 = 0, .opc2 = 0,
-      .access = PL1_RW,
+      .access = PL1_RW, .type = ARM_CP_NO_MIGRATE,
       .fieldoffset = offsetof(CPUARMState, cp15.c5_data), .resetvalue = 0,
       .readfn = pmsav5_data_ap_read, .writefn = pmsav5_data_ap_write, },
     { .name = "INSN_AP", .cp = 15, .crn = 5, .crm = 0, .opc1 = 0, .opc2 = 1,
-      .access = PL1_RW,
+      .access = PL1_RW, .type = ARM_CP_NO_MIGRATE,
       .fieldoffset = offsetof(CPUARMState, cp15.c5_insn), .resetvalue = 0,
       .readfn = pmsav5_insn_ap_read, .writefn = pmsav5_insn_ap_write, },
     { .name = "DATA_EXT_AP", .cp = 15, .crn = 5, .crm = 0, .opc1 = 0, .opc2 = 2,
@@ -801,6 +826,7 @@ static const ARMCPRegInfo omap_cp_reginfo[] = {
       .writefn = omap_threadid_write },
     { .name = "TI925T_STATUS", .cp = 15, .crn = 15,
       .crm = 8, .opc1 = 0, .opc2 = 0, .access = PL1_RW,
+      .type = ARM_CP_NO_MIGRATE,
       .readfn = arm_cp_read_zero, .writefn = omap_wfi_write, },
     /* TODO: Peripheral port remap register:
      * On OMAP2 mcr p15, 0, rn, c15, c2, 4 sets up the interrupt controller
@@ -808,7 +834,8 @@ static const ARMCPRegInfo omap_cp_reginfo[] = {
      * when MMU is off.
      */
     { .name = "OMAP_CACHEMAINT", .cp = 15, .crn = 7, .crm = CP_ANY,
-      .opc1 = 0, .opc2 = CP_ANY, .access = PL1_W, .type = ARM_CP_OVERRIDE,
+      .opc1 = 0, .opc2 = CP_ANY, .access = PL1_W,
+      .type = ARM_CP_OVERRIDE | ARM_CP_NO_MIGRATE,
       .writefn = omap_cachemaint_write },
     { .name = "C9", .cp = 15, .crn = 9,
       .crm = CP_ANY, .opc1 = CP_ANY, .opc2 = CP_ANY, .access = PL1_RW,
@@ -848,7 +875,8 @@ static const ARMCPRegInfo dummy_c15_cp_reginfo[] = {
      */
     { .name = "C15_IMPDEF", .cp = 15, .crn = 15,
       .crm = CP_ANY, .opc1 = CP_ANY, .opc2 = CP_ANY,
-      .access = PL1_RW, .type = ARM_CP_CONST, .resetvalue = 0 },
+      .access = PL1_RW, .type = ARM_CP_CONST | ARM_CP_NO_MIGRATE,
+      .resetvalue = 0 },
     REGINFO_SENTINEL
 };
 
@@ -894,8 +922,8 @@ static const ARMCPRegInfo strongarm_cp_reginfo[] = {
     /* Ignore ReadBuffer accesses */
     { .name = "C9_READBUFFER", .cp = 15, .crn = 9,
       .crm = CP_ANY, .opc1 = CP_ANY, .opc2 = CP_ANY,
-      .access = PL1_RW, .type = ARM_CP_CONST | ARM_CP_OVERRIDE,
-      .resetvalue = 0 },
+      .access = PL1_RW, .resetvalue = 0,
+      .type = ARM_CP_CONST | ARM_CP_OVERRIDE | ARM_CP_NO_MIGRATE },
     REGINFO_SENTINEL
 };
 
@@ -920,7 +948,7 @@ static int mpidr_read(CPUARMState *env, const ARMCPRegInfo *ri,
 
 static const ARMCPRegInfo mpidr_cp_reginfo[] = {
     { .name = "MPIDR", .cp = 15, .crn = 0, .crm = 0, .opc1 = 0, .opc2 = 5,
-      .access = PL1_R, .readfn = mpidr_read },
+      .access = PL1_R, .readfn = mpidr_read, .type = ARM_CP_NO_MIGRATE },
     REGINFO_SENTINEL
 };
 
@@ -1103,7 +1131,8 @@ void register_cp_regs_for_features(ARMCPU *cpu)
             .name = "PMCR", .cp = 15, .crn = 9, .crm = 12, .opc1 = 0, .opc2 = 0,
             .access = PL0_RW, .resetvalue = cpu->midr & 0xff000000,
             .fieldoffset = offsetof(CPUARMState, cp15.c9_pmcr),
-            .readfn = pmreg_read, .writefn = pmcr_write
+            .readfn = pmreg_read, .writefn = pmcr_write,
+            .raw_readfn = raw_read, .raw_writefn = raw_write,
         };
         ARMCPRegInfo clidr = {
             .name = "CLIDR", .cp = 15, .crn = 0, .crm = 0, .opc1 = 1, .opc2 = 1,
@@ -1175,7 +1204,7 @@ void register_cp_regs_for_features(ARMCPU *cpu)
             { .name = "MIDR",
               .cp = 15, .crn = 0, .crm = 0, .opc1 = 0, .opc2 = 0,
               .access = PL1_R, .resetvalue = cpu->midr,
-              .writefn = arm_cp_write_ignore,
+              .writefn = arm_cp_write_ignore, .raw_writefn = raw_write,
               .fieldoffset = offsetof(CPUARMState, cp15.c0_cpuid) },
             { .name = "CTR",
               .cp = 15, .crn = 0, .crm = 0, .opc1 = 0, .opc2 = 1,