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target/arm/kvm: Move kvm_arm_get_host_cpu_features and unexport
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Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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@rth7680 @pm215
rth7680 authored and pm215 committed Dec 19, 2023
1 parent 21beccd commit dc40d45
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Showing 3 changed files with 265 additions and 276 deletions.
265 changes: 265 additions & 0 deletions target/arm/kvm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,17 @@ static bool cap_has_mp_state;
static bool cap_has_inject_serror_esr;
static bool cap_has_inject_ext_dabt;

/**
* ARMHostCPUFeatures: information about the host CPU (identified
* by asking the host kernel)
*/
typedef struct ARMHostCPUFeatures {
ARMISARegisters isar;
uint64_t features;
uint32_t target;
const char *dtb_compatible;
} ARMHostCPUFeatures;

static ARMHostCPUFeatures arm_host_cpu_features;

int kvm_arm_vcpu_init(CPUState *cs)
Expand Down Expand Up @@ -167,6 +178,260 @@ void kvm_arm_destroy_scratch_host_vcpu(int *fdarray)
}
}

static int read_sys_reg32(int fd, uint32_t *pret, uint64_t id)
{
uint64_t ret;
struct kvm_one_reg idreg = { .id = id, .addr = (uintptr_t)&ret };
int err;

assert((id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U64);
err = ioctl(fd, KVM_GET_ONE_REG, &idreg);
if (err < 0) {
return -1;
}
*pret = ret;
return 0;
}

static int read_sys_reg64(int fd, uint64_t *pret, uint64_t id)
{
struct kvm_one_reg idreg = { .id = id, .addr = (uintptr_t)pret };

assert((id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U64);
return ioctl(fd, KVM_GET_ONE_REG, &idreg);
}

static bool kvm_arm_pauth_supported(void)
{
return (kvm_check_extension(kvm_state, KVM_CAP_ARM_PTRAUTH_ADDRESS) &&
kvm_check_extension(kvm_state, KVM_CAP_ARM_PTRAUTH_GENERIC));
}

static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
{
/* Identify the feature bits corresponding to the host CPU, and
* fill out the ARMHostCPUClass fields accordingly. To do this
* we have to create a scratch VM, create a single CPU inside it,
* and then query that CPU for the relevant ID registers.
*/
int fdarray[3];
bool sve_supported;
bool pmu_supported = false;
uint64_t features = 0;
int err;

/* Old kernels may not know about the PREFERRED_TARGET ioctl: however
* we know these will only support creating one kind of guest CPU,
* which is its preferred CPU type. Fortunately these old kernels
* support only a very limited number of CPUs.
*/
static const uint32_t cpus_to_try[] = {
KVM_ARM_TARGET_AEM_V8,
KVM_ARM_TARGET_FOUNDATION_V8,
KVM_ARM_TARGET_CORTEX_A57,
QEMU_KVM_ARM_TARGET_NONE
};
/*
* target = -1 informs kvm_arm_create_scratch_host_vcpu()
* to use the preferred target
*/
struct kvm_vcpu_init init = { .target = -1, };

/*
* Ask for SVE if supported, so that we can query ID_AA64ZFR0,
* which is otherwise RAZ.
*/
sve_supported = kvm_arm_sve_supported();
if (sve_supported) {
init.features[0] |= 1 << KVM_ARM_VCPU_SVE;
}

/*
* Ask for Pointer Authentication if supported, so that we get
* the unsanitized field values for AA64ISAR1_EL1.
*/
if (kvm_arm_pauth_supported()) {
init.features[0] |= (1 << KVM_ARM_VCPU_PTRAUTH_ADDRESS |
1 << KVM_ARM_VCPU_PTRAUTH_GENERIC);
}

if (kvm_arm_pmu_supported()) {
init.features[0] |= 1 << KVM_ARM_VCPU_PMU_V3;
pmu_supported = true;
}

if (!kvm_arm_create_scratch_host_vcpu(cpus_to_try, fdarray, &init)) {
return false;
}

ahcf->target = init.target;
ahcf->dtb_compatible = "arm,arm-v8";

err = read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64pfr0,
ARM64_SYS_REG(3, 0, 0, 4, 0));
if (unlikely(err < 0)) {
/*
* Before v4.15, the kernel only exposed a limited number of system
* registers, not including any of the interesting AArch64 ID regs.
* For the most part we could leave these fields as zero with minimal
* effect, since this does not affect the values seen by the guest.
*
* However, it could cause problems down the line for QEMU,
* so provide a minimal v8.0 default.
*
* ??? Could read MIDR and use knowledge from cpu64.c.
* ??? Could map a page of memory into our temp guest and
* run the tiniest of hand-crafted kernels to extract
* the values seen by the guest.
* ??? Either of these sounds like too much effort just
* to work around running a modern host kernel.
*/
ahcf->isar.id_aa64pfr0 = 0x00000011; /* EL1&0, AArch64 only */
err = 0;
} else {
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64pfr1,
ARM64_SYS_REG(3, 0, 0, 4, 1));
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64smfr0,
ARM64_SYS_REG(3, 0, 0, 4, 5));
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64dfr0,
ARM64_SYS_REG(3, 0, 0, 5, 0));
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64dfr1,
ARM64_SYS_REG(3, 0, 0, 5, 1));
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64isar0,
ARM64_SYS_REG(3, 0, 0, 6, 0));
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64isar1,
ARM64_SYS_REG(3, 0, 0, 6, 1));
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64isar2,
ARM64_SYS_REG(3, 0, 0, 6, 2));
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64mmfr0,
ARM64_SYS_REG(3, 0, 0, 7, 0));
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64mmfr1,
ARM64_SYS_REG(3, 0, 0, 7, 1));
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64mmfr2,
ARM64_SYS_REG(3, 0, 0, 7, 2));

/*
* Note that if AArch32 support is not present in the host,
* the AArch32 sysregs are present to be read, but will
* return UNKNOWN values. This is neither better nor worse
* than skipping the reads and leaving 0, as we must avoid
* considering the values in every case.
*/
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_pfr0,
ARM64_SYS_REG(3, 0, 0, 1, 0));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_pfr1,
ARM64_SYS_REG(3, 0, 0, 1, 1));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_dfr0,
ARM64_SYS_REG(3, 0, 0, 1, 2));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_mmfr0,
ARM64_SYS_REG(3, 0, 0, 1, 4));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_mmfr1,
ARM64_SYS_REG(3, 0, 0, 1, 5));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_mmfr2,
ARM64_SYS_REG(3, 0, 0, 1, 6));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_mmfr3,
ARM64_SYS_REG(3, 0, 0, 1, 7));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_isar0,
ARM64_SYS_REG(3, 0, 0, 2, 0));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_isar1,
ARM64_SYS_REG(3, 0, 0, 2, 1));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_isar2,
ARM64_SYS_REG(3, 0, 0, 2, 2));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_isar3,
ARM64_SYS_REG(3, 0, 0, 2, 3));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_isar4,
ARM64_SYS_REG(3, 0, 0, 2, 4));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_isar5,
ARM64_SYS_REG(3, 0, 0, 2, 5));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_mmfr4,
ARM64_SYS_REG(3, 0, 0, 2, 6));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_isar6,
ARM64_SYS_REG(3, 0, 0, 2, 7));

err |= read_sys_reg32(fdarray[2], &ahcf->isar.mvfr0,
ARM64_SYS_REG(3, 0, 0, 3, 0));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.mvfr1,
ARM64_SYS_REG(3, 0, 0, 3, 1));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.mvfr2,
ARM64_SYS_REG(3, 0, 0, 3, 2));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_pfr2,
ARM64_SYS_REG(3, 0, 0, 3, 4));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_dfr1,
ARM64_SYS_REG(3, 0, 0, 3, 5));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_mmfr5,
ARM64_SYS_REG(3, 0, 0, 3, 6));

/*
* DBGDIDR is a bit complicated because the kernel doesn't
* provide an accessor for it in 64-bit mode, which is what this
* scratch VM is in, and there's no architected "64-bit sysreg
* which reads the same as the 32-bit register" the way there is
* for other ID registers. Instead we synthesize a value from the
* AArch64 ID_AA64DFR0, the same way the kernel code in
* arch/arm64/kvm/sys_regs.c:trap_dbgidr() does.
* We only do this if the CPU supports AArch32 at EL1.
*/
if (FIELD_EX32(ahcf->isar.id_aa64pfr0, ID_AA64PFR0, EL1) >= 2) {
int wrps = FIELD_EX64(ahcf->isar.id_aa64dfr0, ID_AA64DFR0, WRPS);
int brps = FIELD_EX64(ahcf->isar.id_aa64dfr0, ID_AA64DFR0, BRPS);
int ctx_cmps =
FIELD_EX64(ahcf->isar.id_aa64dfr0, ID_AA64DFR0, CTX_CMPS);
int version = 6; /* ARMv8 debug architecture */
bool has_el3 =
!!FIELD_EX32(ahcf->isar.id_aa64pfr0, ID_AA64PFR0, EL3);
uint32_t dbgdidr = 0;

dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, WRPS, wrps);
dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, BRPS, brps);
dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, CTX_CMPS, ctx_cmps);
dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, VERSION, version);
dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, NSUHD_IMP, has_el3);
dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, SE_IMP, has_el3);
dbgdidr |= (1 << 15); /* RES1 bit */
ahcf->isar.dbgdidr = dbgdidr;
}

if (pmu_supported) {
/* PMCR_EL0 is only accessible if the vCPU has feature PMU_V3 */
err |= read_sys_reg64(fdarray[2], &ahcf->isar.reset_pmcr_el0,
ARM64_SYS_REG(3, 3, 9, 12, 0));
}

if (sve_supported) {
/*
* There is a range of kernels between kernel commit 73433762fcae
* and f81cb2c3ad41 which have a bug where the kernel doesn't
* expose SYS_ID_AA64ZFR0_EL1 via the ONE_REG API unless the VM has
* enabled SVE support, which resulted in an error rather than RAZ.
* So only read the register if we set KVM_ARM_VCPU_SVE above.
*/
err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64zfr0,
ARM64_SYS_REG(3, 0, 0, 4, 4));
}
}

kvm_arm_destroy_scratch_host_vcpu(fdarray);

if (err < 0) {
return false;
}

/*
* We can assume any KVM supporting CPU is at least a v8
* with VFPv4+Neon; this in turn implies most of the other
* feature bits.
*/
features |= 1ULL << ARM_FEATURE_V8;
features |= 1ULL << ARM_FEATURE_NEON;
features |= 1ULL << ARM_FEATURE_AARCH64;
features |= 1ULL << ARM_FEATURE_PMU;
features |= 1ULL << ARM_FEATURE_GENERIC_TIMER;

ahcf->features = features;

return true;
}

void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
{
CPUARMState *env = &cpu->env;
Expand Down

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