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target/arm: Read debug-related ID registers from KVM

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Now we have isar_feature test functions that look at fields in the
ID_AA64DFR0_EL1 and ID_DFR0 ID registers, add the code that reads
these register values from KVM so that the checks behave correctly
when we're using KVM.

No isar_feature function tests ID_AA64DFR1_EL1 or DBGDIDR yet, but we
add it to maintain the invariant that every field in the
ARMISARegisters struct is populated for a KVM CPU and can be relied
on.  This requirement isn't actually written down yet, so add a note
to the relevant comment.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200214175116.9164-13-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2020-02-14 17:51:07 +00:00
parent 4426d3617d
commit 1548a7b2ad
3 changed files with 49 additions and 0 deletions
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5
target/arm/cpu.h
View File

@ -853,6 +853,11 @@ struct ARMCPU {
* prefix means a constant register.
* Some of these registers are split out into a substructure that
* is shared with the translators to control the ISA.
*
* Note that if you add an ID register to the ARMISARegisters struct
* you need to also update the 32-bit and 64-bit versions of the
* kvm_arm_get_host_cpu_features() function to correctly populate the
* field by reading the value from the KVM vCPU.
*/
struct ARMISARegisters {
uint32_t id_isar0;

8
target/arm/kvm32.c
View File

@ -97,6 +97,9 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
ahcf->isar.id_isar6 = 0;
}
err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_dfr0,
ARM_CP15_REG32(0, 0, 1, 2));
err |= read_sys_reg32(fdarray[2], &ahcf->isar.mvfr0,
KVM_REG_ARM | KVM_REG_SIZE_U32 |
KVM_REG_ARM_VFP | KVM_REG_ARM_VFP_MVFR0);
@ -108,6 +111,11 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
* Fortunately there is not yet anything in there that affects migration.
*/
/*
* There is no way to read DBGDIDR, because currently 32-bit KVM
* doesn't implement debug at all. Leave it at zero.
*/
kvm_arm_destroy_scratch_host_vcpu(fdarray);
if (err < 0) {

36
target/arm/kvm64.c
View File

@ -541,6 +541,10 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
} 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_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,
@ -559,6 +563,8 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
* 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_dfr0,
ARM64_SYS_REG(3, 0, 0, 1, 2));
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,
@ -580,6 +586,36 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
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));
/*
* 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;
}
}
sve_supported = ioctl(fdarray[0], KVM_CHECK_EXTENSION, KVM_CAP_ARM_SVE) > 0;