@@ -2558,25 +2558,18 @@ bool write_list_to_cpustate(ARMCPU *cpu);
/**
* write_cpustate_to_list:
* @cpu: ARMCPU
- * @kvm_sync: true if this is for syncing back to KVM
*
* For each register listed in the ARMCPU cpreg_indexes list, write
* its value from the ARMCPUState structure into the cpreg_values list.
* This is used to copy info from TCG's working data structures into
* KVM or for outbound migration.
*
- * @kvm_sync is true if we are doing this in order to sync the
- * register state back to KVM. In this case we will only update
- * values in the list if the previous list->cpustate sync actually
- * successfully wrote the CPU state. Otherwise we will keep the value
- * that is in the list.
- *
* Returns: true if all register values were read correctly,
* false if some register was unknown or could not be read.
* Note that we do not stop early on failure -- we will attempt
* reading all registers in the list.
*/
-bool write_cpustate_to_list(ARMCPU *cpu, bool kvm_sync);
+bool write_cpustate_to_list(ARMCPU *cpu);
#define ARM_CPUID_TI915T 0x54029152
#define ARM_CPUID_TI925T 0x54029252
@@ -265,7 +265,7 @@ static bool raw_accessors_invalid(const ARMCPRegInfo *ri)
return true;
}
-bool write_cpustate_to_list(ARMCPU *cpu, bool kvm_sync)
+bool write_cpustate_to_list(ARMCPU *cpu)
{
/* Write the coprocessor state from cpu->env to the (index,value) list. */
int i;
@@ -274,7 +274,6 @@ bool write_cpustate_to_list(ARMCPU *cpu, bool kvm_sync)
for (i = 0; i < cpu->cpreg_array_len; i++) {
uint32_t regidx = kvm_to_cpreg_id(cpu->cpreg_indexes[i]);
const ARMCPRegInfo *ri;
- uint64_t newval;
ri = get_arm_cp_reginfo(cpu->cp_regs, regidx);
if (!ri) {
@@ -284,29 +283,7 @@ bool write_cpustate_to_list(ARMCPU *cpu, bool kvm_sync)
if (ri->type & ARM_CP_NO_RAW) {
continue;
}
-
- newval = read_raw_cp_reg(&cpu->env, ri);
- if (kvm_sync) {
- /*
- * Only sync if the previous list->cpustate sync succeeded.
- * Rather than tracking the success/failure state for every
- * item in the list, we just recheck "does the raw write we must
- * have made in write_list_to_cpustate() read back OK" here.
- */
- uint64_t oldval = cpu->cpreg_values[i];
-
- if (oldval == newval) {
- continue;
- }
-
- write_raw_cp_reg(&cpu->env, ri, oldval);
- if (read_raw_cp_reg(&cpu->env, ri) != oldval) {
- continue;
- }
-
- write_raw_cp_reg(&cpu->env, ri, newval);
- }
- cpu->cpreg_values[i] = newval;
+ cpu->cpreg_values[i] = read_raw_cp_reg(&cpu->env, ri);
}
return ok;
}
@@ -384,8 +384,24 @@ int kvm_arch_put_registers(CPUState *cs, int level)
return ret;
}
- write_cpustate_to_list(cpu, true);
-
+ /* Note that we do not call write_cpustate_to_list()
+ * here, so we are only writing the tuple list back to
+ * KVM. This is safe because nothing can change the
+ * CPUARMState cp15 fields (in particular gdb accesses cannot)
+ * and so there are no changes to sync. In fact syncing would
+ * be wrong at this point: for a constant register where TCG and
+ * KVM disagree about its value, the preceding write_list_to_cpustate()
+ * would not have had any effect on the CPUARMState value (since the
+ * register is read-only), and a write_cpustate_to_list() here would
+ * then try to write the TCG value back into KVM -- this would either
+ * fail or incorrectly change the value the guest sees.
+ *
+ * If we ever want to allow the user to modify cp15 registers via
+ * the gdb stub, we would need to be more clever here (for instance
+ * tracking the set of registers kvm_arch_get_registers() successfully
+ * managed to update the CPUARMState with, and only allowing those
+ * to be written back up into the kernel).
+ */
if (!write_list_to_kvmstate(cpu, level)) {
return EINVAL;
}
@@ -838,8 +838,6 @@ int kvm_arch_put_registers(CPUState *cs, int level)
return ret;
}
- write_cpustate_to_list(cpu, true);
-
if (!write_list_to_kvmstate(cpu, level)) {
return EINVAL;
}
@@ -630,7 +630,7 @@ static int cpu_pre_save(void *opaque)
abort();
}
} else {
- if (!write_cpustate_to_list(cpu, false)) {
+ if (!write_cpustate_to_list(cpu)) {
/* This should never fail. */
abort();
}
This reverts commit 823e1b3818f9b10b824ddcd756983b6e2fa68730, which introduces a regression running EDK2 guest firmware under KVM: error: kvm run failed Function not implemented PC=000000013f5a6208 X00=00000000404003c4 X01=000000000000003a X02=0000000000000000 X03=00000000404003c4 X04=0000000000000000 X05=0000000096000046 X06=000000013d2ef270 X07=000000013e3d1710 X08=09010755ffaf8ba8 X09=ffaf8b9cfeeb5468 X10=feeb546409010756 X11=09010757ffaf8b90 X12=feeb50680903068b X13=090306a1ffaf8bc0 X14=0000000000000000 X15=0000000000000000 X16=000000013f872da0 X17=00000000ffffa6ab X18=0000000000000000 X19=000000013f5a92d0 X20=000000013f5a7a78 X21=000000000000003a X22=000000013f5a7ab2 X23=000000013f5a92e8 X24=000000013f631090 X25=0000000000000010 X26=0000000000000100 X27=000000013f89501b X28=000000013e3d14e0 X29=000000013e3d12a0 X30=000000013f5a2518 SP=000000013b7be0b0 PSTATE=404003c4 -Z-- EL1t with [ 3507.926571] kvm [35042]: load/store instruction decoding not implemented in the host dmesg. Revert the change for the moment until we can investigate the cause of the regression. Reported-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- target/arm/cpu.h | 9 +-------- target/arm/helper.c | 27 ++------------------------- target/arm/kvm32.c | 20 ++++++++++++++++++-- target/arm/kvm64.c | 2 -- target/arm/machine.c | 2 +- 5 files changed, 22 insertions(+), 38 deletions(-) -- 2.20.1