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[PATCH v2 01/16] target/ppc: add user write access control for PMU SPRs
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From: |
Daniel Henrique Barboza |
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Subject: |
[PATCH v2 01/16] target/ppc: add user write access control for PMU SPRs |
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Date: |
Tue, 24 Aug 2021 13:30:17 -0300 |
We're going to add PMU support for TCG PPC64 chips, based on IBM POWER8+
emulation and following PowerISA v3.1.
PowerISA v3.1 defines two PMU registers groups, A and B:
- group A contains all performance monitor counters (PMCs), MMCR0, MMCR2
and MMCRA;
- group B contains MMCR1, MMCR3, SIER, SIER2, SIER3, SIAR, SDAR.
Group A have read/write non-privileged access depending on MMCR0_PMCC
bits. Group B is always userspace read only.
Userspace will require to write Group A registers, and at the same time
some Linux PMU selftests deliberately test if we are allowing write
access when we shouldn't. This patch address the access control of Group
A PMU registers by doing the following:
- add a 'pmcc_clear' flag in DisasContext. This will map whether
MMCR0_PMCC bits are cleared by checking HFLAGS_PMCCCLEAR;
- create a spr_write_PMU_groupA_ureg() that will be used to all
userspace writes of PMU regs. The reg will apply the proper access
control before forwarding execution to spr_write_ureg().
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
target/ppc/cpu.h | 4 ++++
target/ppc/cpu_init.c | 18 +++++++++---------
target/ppc/helper_regs.c | 3 +++
target/ppc/spr_tcg.h | 1 +
target/ppc/translate.c | 37 +++++++++++++++++++++++++++++++++++++
5 files changed, 54 insertions(+), 9 deletions(-)
diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index 500205229c..627fc8d732 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -342,6 +342,9 @@ typedef struct ppc_v3_pate_t {
#define MSR_RI 1 /* Recoverable interrupt 1 */
#define MSR_LE 0 /* Little-endian mode 1 hflags */
+/* PMU bits */
+#define MMCR0_PMCC PPC_BITMASK(44, 45) /* PMC Control */
+
/* LPCR bits */
#define LPCR_VPM0 PPC_BIT(0)
#define LPCR_VPM1 PPC_BIT(1)
@@ -606,6 +609,7 @@ enum {
HFLAGS_SE = 10, /* MSR_SE -- from elsewhere on embedded ppc */
HFLAGS_FP = 13, /* MSR_FP */
HFLAGS_PR = 14, /* MSR_PR */
+ HFLAGS_PMCCCLEAR = 15, /* PMU MMCR0 PMCC equal to 0b00 */
HFLAGS_VSX = 23, /* MSR_VSX if cpu has VSX */
HFLAGS_VR = 25, /* MSR_VR if cpu has VRE */
diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
index 66deb18a6b..c72c7fabea 100644
--- a/target/ppc/cpu_init.c
+++ b/target/ppc/cpu_init.c
@@ -6868,7 +6868,7 @@ static void register_book3s_pmu_sup_sprs(CPUPPCState *env)
static void register_book3s_pmu_user_sprs(CPUPPCState *env)
{
spr_register(env, SPR_POWER_UMMCR0, "UMMCR0",
- &spr_read_ureg, SPR_NOACCESS,
+ &spr_read_ureg, &spr_write_PMU_groupA_ureg,
&spr_read_ureg, &spr_write_ureg,
0x00000000);
spr_register(env, SPR_POWER_UMMCR1, "UMMCR1",
@@ -6876,31 +6876,31 @@ static void register_book3s_pmu_user_sprs(CPUPPCState
*env)
&spr_read_ureg, &spr_write_ureg,
0x00000000);
spr_register(env, SPR_POWER_UMMCRA, "UMMCRA",
- &spr_read_ureg, SPR_NOACCESS,
+ &spr_read_ureg, &spr_write_PMU_groupA_ureg,
&spr_read_ureg, &spr_write_ureg,
0x00000000);
spr_register(env, SPR_POWER_UPMC1, "UPMC1",
- &spr_read_ureg, SPR_NOACCESS,
+ &spr_read_ureg, &spr_write_PMU_groupA_ureg,
&spr_read_ureg, &spr_write_ureg,
0x00000000);
spr_register(env, SPR_POWER_UPMC2, "UPMC2",
- &spr_read_ureg, SPR_NOACCESS,
+ &spr_read_ureg, &spr_write_PMU_groupA_ureg,
&spr_read_ureg, &spr_write_ureg,
0x00000000);
spr_register(env, SPR_POWER_UPMC3, "UPMC3",
- &spr_read_ureg, SPR_NOACCESS,
+ &spr_read_ureg, &spr_write_PMU_groupA_ureg,
&spr_read_ureg, &spr_write_ureg,
0x00000000);
spr_register(env, SPR_POWER_UPMC4, "UPMC4",
- &spr_read_ureg, SPR_NOACCESS,
+ &spr_read_ureg, &spr_write_PMU_groupA_ureg,
&spr_read_ureg, &spr_write_ureg,
0x00000000);
spr_register(env, SPR_POWER_UPMC5, "UPMC5",
- &spr_read_ureg, SPR_NOACCESS,
+ &spr_read_ureg, &spr_write_PMU_groupA_ureg,
&spr_read_ureg, &spr_write_ureg,
0x00000000);
spr_register(env, SPR_POWER_UPMC6, "UPMC6",
- &spr_read_ureg, SPR_NOACCESS,
+ &spr_read_ureg, &spr_write_PMU_groupA_ureg,
&spr_read_ureg, &spr_write_ureg,
0x00000000);
spr_register(env, SPR_POWER_USIAR, "USIAR",
@@ -6976,7 +6976,7 @@ static void register_power8_pmu_sup_sprs(CPUPPCState *env)
static void register_power8_pmu_user_sprs(CPUPPCState *env)
{
spr_register(env, SPR_POWER_UMMCR2, "UMMCR2",
- &spr_read_ureg, SPR_NOACCESS,
+ &spr_read_ureg, &spr_write_PMU_groupA_ureg,
&spr_read_ureg, &spr_write_ureg,
0x00000000);
spr_register(env, SPR_POWER_USIER, "USIER",
diff --git a/target/ppc/helper_regs.c b/target/ppc/helper_regs.c
index 405450d863..4c1d9575ac 100644
--- a/target/ppc/helper_regs.c
+++ b/target/ppc/helper_regs.c
@@ -106,6 +106,9 @@ static uint32_t hreg_compute_hflags_value(CPUPPCState *env)
if (env->spr[SPR_LPCR] & LPCR_GTSE) {
hflags |= 1 << HFLAGS_GTSE;
}
+ if (((env->spr[SPR_POWER_MMCR0] & MMCR0_PMCC) >> 18) == 0) {
+ hflags |= 1 << HFLAGS_PMCCCLEAR;
+ }
#ifndef CONFIG_USER_ONLY
if (!env->has_hv_mode || (msr & (1ull << MSR_HV))) {
diff --git a/target/ppc/spr_tcg.h b/target/ppc/spr_tcg.h
index 0be5f347d5..027ec4c3f7 100644
--- a/target/ppc/spr_tcg.h
+++ b/target/ppc/spr_tcg.h
@@ -40,6 +40,7 @@ void spr_read_601_rtcl(DisasContext *ctx, int gprn, int sprn);
void spr_read_601_rtcu(DisasContext *ctx, int gprn, int sprn);
void spr_read_spefscr(DisasContext *ctx, int gprn, int sprn);
void spr_write_spefscr(DisasContext *ctx, int sprn, int gprn);
+void spr_write_PMU_groupA_ureg(DisasContext *ctx, int sprn, int gprn);
#ifndef CONFIG_USER_ONLY
void spr_write_generic32(DisasContext *ctx, int sprn, int gprn);
diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 171b216e17..3a1eafbba8 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -175,6 +175,7 @@ struct DisasContext {
bool spe_enabled;
bool tm_enabled;
bool gtse;
+ bool pmcc_clear;
ppc_spr_t *spr_cb; /* Needed to check rights for mfspr/mtspr */
int singlestep_enabled;
uint32_t flags;
@@ -526,6 +527,41 @@ void spr_write_ureg(DisasContext *ctx, int sprn, int gprn)
}
#endif
+#if defined(TARGET_PPC64) && !defined(CONFIG_USER_ONLY)
+/*
+ * User write function for PMU group A regs. PowerISA v3.1
+ * defines Group A sprs as:
+ *
+ * "The non-privileged read/write Performance Monitor registers
+ * (i.e., the PMCs, MMCR0, MMCR2, and MMCRA at SPR numbers
+ * 771-776, 779, 769, and 770, respectively)"
+ *
+ * These SPRs have a common user write access control via
+ * MMCR0 bits 44 and 45 (PMCC).
+ */
+void spr_write_PMU_groupA_ureg(DisasContext *ctx, int sprn, int gprn)
+{
+ /*
+ * For group A PMU sprs, if PMCC = 0b00, PowerISA v3.1
+ * dictates that:
+ *
+ * "If an attempt is made to write to an SPR in group A in
+ * problem state, a Hypervisor Emulation Assistance
+ * interrupt will occur."
+ */
+ if (ctx->pmcc_clear) {
+ gen_hvpriv_exception(ctx, POWERPC_EXCP_INVAL_SPR);
+ return;
+ }
+ spr_write_ureg(ctx, sprn, gprn);
+}
+#else
+void spr_write_PMU_groupA_ureg(DisasContext *ctx, int sprn, int gprn)
+{
+ spr_noaccess(ctx, gprn, sprn);
+}
+#endif
+
/* SPR common to all non-embedded PowerPC */
/* DECR */
#if !defined(CONFIG_USER_ONLY)
@@ -8539,6 +8575,7 @@ static void ppc_tr_init_disas_context(DisasContextBase
*dcbase, CPUState *cs)
ctx->vsx_enabled = (hflags >> HFLAGS_VSX) & 1;
ctx->tm_enabled = (hflags >> HFLAGS_TM) & 1;
ctx->gtse = (hflags >> HFLAGS_GTSE) & 1;
+ ctx->pmcc_clear = (hflags >> HFLAGS_PMCCCLEAR) & 1;
ctx->singlestep_enabled = 0;
if ((hflags >> HFLAGS_SE) & 1) {
--
2.31.1