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target/arm: Use shared helper for KVM_CAP_ARM_RME detection #10

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target/arm: Use shared helper for KVM_CAP_ARM_RME detection #10

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6 changes: 5 additions & 1 deletion target/arm/aarch64-qmp-cmds.c
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Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,11 @@ CcaCapability *qmp_query_cca_capabilities(Error **errp)
return NULL;
}

if (!kvm_check_extension(kvm_state, KVM_CAP_ARM_RME)) {
/*
* Use the runtime-detected KVM_CAP_ARM_RME value to handle
* the ABI change between kernel versions (243 on 6.16, 244 on later).
*/
if (!kvm_check_extension(kvm_state, kvm_arm_rme_get_cap())) {
error_setg(errp, "RME is not enabled in KVM");
return NULL;
}
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45 changes: 32 additions & 13 deletions target/arm/kvm-rme.c
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,37 @@
#include "system/runstate.h"
#include <sys/utsname.h>

/*
* Returns the correct KVM_CAP_ARM_RME capability value for the running kernel.
* This handles the ABI change between kernel versions:
* - Linux 6.16: KVM_CAP_ARM_RME == 243
* - Linux 6.17+: KVM_CAP_ARM_RME == 244
*/
unsigned int kvm_arm_rme_get_cap(void)
{
static unsigned int rme_cap = 0;
static bool detected = false;

if (!detected) {
struct utsname buf;
int major, minor;

rme_cap = KVM_CAP_ARM_RME;

if (uname(&buf) == 0) {
if (sscanf(buf.release, "%d.%d", &major, &minor) == 2) {
/* For Linux kernel v6.16, KVM_CAP_ARM_RME == 243 */
if ((major == 6) && (minor == 16)) {
rme_cap = 243;
}
}
}
detected = true;
}

return rme_cap;
}

#define TYPE_RME_GUEST "rme-guest"
OBJECT_DECLARE_SIMPLE_TYPE(RmeGuest, RME_GUEST)

Expand Down Expand Up @@ -788,9 +819,6 @@ static void rme_guest_class_init(ObjectClass *oc, const void *data)

static void rme_guest_init(Object *obj)
{
struct utsname buf;
int major, minor;

if (rme_guest) {
error_report("a single instance of RmeGuest is supported");
exit(1);
Expand All @@ -800,16 +828,7 @@ static void rme_guest_init(Object *obj)
rme_guest->measurement_algo = RME_GUEST_MEASUREMENT_ALGORITHM_SHA512;
rme_guest->mec_specified = false;

rme_guest->rme_capable = KVM_CAP_ARM_RME;

if (uname(&buf) == 0) {
if (sscanf(buf.release, "%d.%d", &major, &minor) == 2) {
/* For Linux kernel v6.16, KVM_CAP_ARM_RME == 243 */
if ((major == 6) && (minor == 16)) {
rme_guest->rme_capable = 243;
}
}
}
rme_guest->rme_capable = kvm_arm_rme_get_cap();
}

static void rme_guest_finalize(Object *obj)
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9 changes: 9 additions & 0 deletions target/arm/kvm_arm.h
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Expand Up @@ -274,6 +274,15 @@ void kvm_arm_enable_mte(Object *cpuobj, Error **errp);

void arm_cpu_kvm_set_irq(void *arm_cpu, int irq, int level);

/**
* kvm_arm_rme_get_cap:
*
* Returns the correct KVM_CAP_ARM_RME capability value for the running
* kernel. This handles the ABI change between kernel versions where the
* capability number differs (e.g., 243 on kernel 6.16, 244 on later kernels).
*/
unsigned int kvm_arm_rme_get_cap(void);

/**
* kvm_arm_rme_init
* @ms: the machine state
Expand Down