diff mbox series

target/arm/helper: Propagate MDCR_EL2.HPMN into PMCR_EL0.N

Message ID 20231215144652.4193815-2-jean-philippe@linaro.org
State Accepted
Commit 6980c31dec42b6daebf7fec13b2d39ed87bb4766
Headers show
Series target/arm/helper: Propagate MDCR_EL2.HPMN into PMCR_EL0.N | expand

Commit Message

Jean-Philippe Brucker Dec. 15, 2023, 2:46 p.m. UTC 
MDCR_EL2.HPMN allows an hypervisor to limit the number of PMU counters
available to EL1 and EL0 (to keep the others to itself). QEMU already
implements this split correctly, except for PMCR_EL0.N reads: the number
of counters read by EL1 or EL0 should be the one configured in
MDCR_EL2.HPMN.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 target/arm/helper.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

Comments

Peter Maydell Dec. 18, 2023, 3:05 p.m. UTC | #1 
On Fri, 15 Dec 2023 at 15:16, Jean-Philippe Brucker
<jean-philippe@linaro.org> wrote:
>
> MDCR_EL2.HPMN allows an hypervisor to limit the number of PMU counters
> available to EL1 and EL0 (to keep the others to itself). QEMU already
> implements this split correctly, except for PMCR_EL0.N reads: the number
> of counters read by EL1 or EL0 should be the one configured in
> MDCR_EL2.HPMN.
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

Applied to target-arm.next for 9.0, thanks. I've added a
Cc: qemu-stable@nongnu.org because it seems a fix worth
backporting.

-- PMM
diff mbox series

Patch

diff --git a/target/arm/helper.c b/target/arm/helper.c
index ff1970981e..bec293bc93 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -1475,6 +1475,22 @@  static void pmcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
     pmu_op_finish(env);
 }
 
+static uint64_t pmcr_read(CPUARMState *env, const ARMCPRegInfo *ri)
+{
+    uint64_t pmcr = env->cp15.c9_pmcr;
+
+    /*
+     * If EL2 is implemented and enabled for the current security state, reads
+     * of PMCR.N from EL1 or EL0 return the value of MDCR_EL2.HPMN or HDCR.HPMN.
+     */
+    if (arm_current_el(env) <= 1 && arm_is_el2_enabled(env)) {
+        pmcr &= ~PMCRN_MASK;
+        pmcr |= (env->cp15.mdcr_el2 & MDCR_HPMN) << PMCRN_SHIFT;
+    }
+
+    return pmcr;
+}
+
 static void pmswinc_write(CPUARMState *env, const ARMCPRegInfo *ri,
                           uint64_t value)
 {
@@ -7137,8 +7153,9 @@  static void define_pmu_regs(ARMCPU *cpu)
         .fgt = FGT_PMCR_EL0,
         .type = ARM_CP_IO | ARM_CP_ALIAS,
         .fieldoffset = offsetoflow32(CPUARMState, cp15.c9_pmcr),
-        .accessfn = pmreg_access, .writefn = pmcr_write,
-        .raw_writefn = raw_write,
+        .accessfn = pmreg_access,
+        .readfn = pmcr_read, .raw_readfn = raw_read,
+        .writefn = pmcr_write, .raw_writefn = raw_write,
     };
     ARMCPRegInfo pmcr64 = {
         .name = "PMCR_EL0", .state = ARM_CP_STATE_AA64,
@@ -7148,6 +7165,7 @@  static void define_pmu_regs(ARMCPU *cpu)
         .type = ARM_CP_IO,
         .fieldoffset = offsetof(CPUARMState, cp15.c9_pmcr),
         .resetvalue = cpu->isar.reset_pmcr_el0,
+        .readfn = pmcr_read, .raw_readfn = raw_read,
         .writefn = pmcr_write, .raw_writefn = raw_write,
     };