On 2025/4/15 0:38, Cornelia Huck wrote:
From: Eric Auger <eric.au...@redhat.com>
We want to give a chance to override the value of host ID regs.
In a previous patch we made sure all their values could be fetched
through kvm_get_one_reg() calls before their modification. After
their potential modification we need to make sure we write back
the values through kvm_set_one_reg() calls.
Make sure the cpreg_list is modified with updated values and
transfer those values back to kvm.
Signed-off-by: Eric Auger <eric.au...@redhat.com>
Signed-off-by: Cornelia Huck <coh...@redhat.com>
---
target/arm/kvm.c | 44 ++++++++++++++++++++++++++++++++++++++++-
target/arm/trace-events | 1 +
2 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index b07d5f16db50..9e4cca1705c8 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -1083,6 +1083,39 @@ void kvm_arm_cpu_post_load(ARMCPU *cpu)
}
}
+static void kvm_arm_writable_idregs_to_cpreg_list(ARMCPU *cpu)
+{
+ if (!cpu->writable_map) {
+ return;
+ }
+ for (int i = 0; i < NR_ID_REGS; i++) {
+ uint64_t writable_mask = cpu->writable_map->regs[i];
+ uint64_t *cpreg;
+
+ if (writable_mask) {
+ uint64_t previous, new;
+ int idx = kvm_idx_to_idregs_idx(i);
+ ARM64SysReg *sysregdesc;
+ uint32_t sysreg;
+
+ if (idx == -1) {
+ /* sysreg writable, but we don't know it */
+ continue;
+ }
+ sysregdesc = &arm64_id_regs[idx];
+ sysreg = sysregdesc->sysreg;
+ cpreg = kvm_arm_get_cpreg_ptr(cpu,
idregs_sysreg_to_kvm_reg(sysreg));
+ previous = *cpreg;
+ new = cpu->isar.idregs[idx];
+ if (previous != new) {
+ *cpreg = new;
+ trace_kvm_arm_writable_idregs_to_cpreg_list(sysregdesc->name,
+ previous, new);
+ }
+ }
+ }
+}
+
void kvm_arm_reset_vcpu(ARMCPU *cpu)
{
int ret;
@@ -2050,7 +2083,16 @@ int kvm_arch_init_vcpu(CPUState *cs)
}
cpu->mp_affinity = mpidr & ARM64_AFFINITY_MASK;
- return kvm_arm_init_cpreg_list(cpu);
+ ret = kvm_arm_init_cpreg_list(cpu);
+ if (ret) {
+ return ret;
+ }
+ /* overwrite writable ID regs with their updated property values */
+ kvm_arm_writable_idregs_to_cpreg_list(cpu);
+
+ write_list_to_kvmstate(cpu, 3);
+
+ return 0;
}
Hi,
When I was testing this series, I found a problem. On the host,
SYSREG_ID_AA64MMFR3_EL1_TCRX=0x1,
I configured it to 0x0 in qemu, and qemu cannot start.
The ID_AA64MMFR3_EL1 TCRX field controls whether the TCR2_EL1 and
TCR2_EL2 registers are used.
In the kernel, when TCRX is 0, TCR2_EL1 is invisible to the guest, and
when it is 1, it is visible. When we
configure this field segment to 0, the configuration is not yet written
to KVM, but the cpreg list is initialized,
adding TCR2_EL1 to the cpreg list. Therefore, after writing the
QEMU-configured registers to KVM, the
cpreg list needs to be updated again.
@@ -2227,7 +2229,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
write_list_to_kvmstate(cpu, 3);
- return 0;
+ return kvm_arm_init_cpreg_list(cpu);
}
The above modification can solve the problem, but it may not be the best
way.
Thanks,
Jinqian
int kvm_arch_destroy_vcpu(CPUState *cs)
diff --git a/target/arm/trace-events b/target/arm/trace-events
index 17e52c0705f2..955149ee1ac4 100644
--- a/target/arm/trace-events
+++ b/target/arm/trace-events
@@ -14,3 +14,4 @@ arm_gt_update_irq(int timer, int irqstate) "gt_update_irq: timer
%d irqstate %d"
# kvm.c
kvm_arm_fixup_msi_route(uint64_t iova, uint64_t gpa) "MSI iova = 0x%"PRIx64" is
translated into 0x%"PRIx64
get_host_cpu_idregs(const char *name, uint64_t value) "scratch vcpu host value for
%s is 0x%"PRIx64
+kvm_arm_writable_idregs_to_cpreg_list(const char *name, uint64_t previous, uint64_t new) "%s
overwrite default 0x%"PRIx64" with 0x%"PRIx64
