On 04/01/2024 16:27, James Clark wrote:

Currently the userspace and kernel filters for guests are never set, so no trace will be generated for them. Add support for tracing guests by passing the desired TRFCR value to KVM so it can be applied to the guest.

By writing either E1TRE or E0TRE, filtering on either guest kernel or guest userspace is also supported. And if both E1TRE and E0TRE are cleared when exclude_guest is set, that option is supported too. This change also brings exclude_host support which is difficult to add as a separate commit without excess churn and resulting in no trace at all.

Testing

The addresses were counted with the following:

$ perf report -D | grep -Eo 'EL2|EL1|EL0' | sort | uniq -c

Guest kernel only:

$ perf record -e cs_etm//Gk -a -- true 535 EL1 1 EL2

Guest user only (only 5 addresses because the guest runs slowly in the model):

$ perf record -e cs_etm//Gu -a -- true 5 EL0

Host kernel only:

$ perf record -e cs_etm//Hk -a -- true 3501 EL2

Host userspace only:

$ perf record -e cs_etm//Hu -a -- true 408 EL0 1 EL2

Signed-off-by: James Clark james.clark@arm.com

Reviewed-by: Suzuki K Poulose suzuki.poulose@arm.com

---

.../coresight/coresight-etm4x-core.c | 42 ++++++++++++++++--- drivers/hwtracing/coresight/coresight-etm4x.h | 2 +- drivers/hwtracing/coresight/coresight-priv.h | 3 ++ 3 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index 34aee59dd147..885d70fd6f40 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -6,6 +6,7 @@ #include <linux/acpi.h> #include <linux/bitops.h> #include <linux/kernel.h> +#include <linux/kvm_host.h> #include <linux/moduleparam.h> #include <linux/init.h> #include <linux/types.h> @@ -271,9 +272,22 @@ static void etm4x_prohibit_trace(struct etmv4_drvdata *drvdata) /* If the CPU doesn't support FEAT_TRF, nothing to do */ if (!drvdata->trfcr) return;

• kvm_etm_set_guest_trfcr(0); cpu_prohibit_trace(); }

+static u64 etm4x_get_kern_user_filter(struct etmv4_drvdata *drvdata) +{

• u64 trfcr = drvdata->trfcr;
• if (drvdata->config.mode & ETM_MODE_EXCL_KERN)

• trfcr &= ~TRFCR_ELx_ExTRE;
  

• if (drvdata->config.mode & ETM_MODE_EXCL_USER)

• trfcr &= ~TRFCR_ELx_E0TRE;
  

• return trfcr;

+}

• /*
  • etm4x_allow_trace - Allow CPU tracing in the respective ELs,
  • as configured by the drvdata->config.mode for the current

@@ -286,18 +300,28 @@ static void etm4x_prohibit_trace(struct etmv4_drvdata *drvdata) */ static void etm4x_allow_trace(struct etmv4_drvdata *drvdata) {

• u64 trfcr = drvdata->trfcr;

• u64 trfcr;

/* If the CPU doesn't support FEAT_TRF, nothing to do */

• if (!trfcr)

• if (!drvdata->trfcr) return;

• if (drvdata->config.mode & ETM_MODE_EXCL_KERN)

• trfcr &= ~TRFCR_ELx_ExTRE;
  

• if (drvdata->config.mode & ETM_MODE_EXCL_USER)

• trfcr &= ~TRFCR_ELx_E0TRE;
  

• if (drvdata->config.mode & ETM_MODE_EXCL_HOST)

• trfcr = drvdata->trfcr & ~(TRFCR_ELx_ExTRE | TRFCR_ELx_E0TRE);
  

• else

• trfcr = etm4x_get_kern_user_filter(drvdata);
  

write_trfcr(trfcr);

• /* Set filters for guests and pass to KVM */
• if (drvdata->config.mode & ETM_MODE_EXCL_GUEST)

• trfcr = drvdata->trfcr & ~(TRFCR_ELx_ExTRE | TRFCR_ELx_E0TRE);
  

• else

• trfcr = etm4x_get_kern_user_filter(drvdata);
  

• /* TRFCR_EL1 doesn't have CX so mask it out. */
• trfcr &= ~TRFCR_EL2_CX;
• kvm_etm_set_guest_trfcr(trfcr); }

#ifdef CONFIG_ETM4X_IMPDEF_FEATURE @@ -655,6 +679,12 @@ static int etm4_parse_event_config(struct coresight_device *csdev, if (attr->exclude_user) config->mode = ETM_MODE_EXCL_USER;

• if (attr->exclude_host)

• config->mode |= ETM_MODE_EXCL_HOST;
  

• if (attr->exclude_guest)

• config->mode |= ETM_MODE_EXCL_GUEST;
  

• /* Always start from the default config */ etm4_set_default_config(config);

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h index 20e2e4cb7614..3f170599822f 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.h +++ b/drivers/hwtracing/coresight/coresight-etm4x.h @@ -841,7 +841,7 @@ enum etm_impdef_type {

• @s_ex_level: Secure ELs where tracing is supported.

*/ struct etmv4_config {

• u32 mode;

• u64 mode; u32 pe_sel; u32 cfg; u32 eventctrl0;

diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index 767076e07970..727dd27ba800 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -39,6 +39,9 @@ #define ETM_MODE_EXCL_KERN BIT(30) #define ETM_MODE_EXCL_USER BIT(31) +#define ETM_MODE_EXCL_HOST BIT(32) +#define ETM_MODE_EXCL_GUEST BIT(33)

• struct cs_pair_attribute { struct device_attribute attr; u32 lo_off;