Re: [PATCH v3 1/6] KVM: arm64: unify code to prepare traps
From: Shaoqin Huang
Date: Mon May 27 2024 - 04:02:15 EST
Hi Sebastian,
On 5/14/24 15:22, Sebastian Ott wrote:
There are 2 functions to calculate traps via HCR_EL2:
* kvm_init_sysreg() called via KVM_RUN (before the 1st run or when
the pid changes)
* vcpu_reset_hcr() called via KVM_ARM_VCPU_INIT
To unify these 2 and to support traps that are dependent on the
ID register configuration, move the code from vcpu_reset_hcr()
to sys_regs.c and call it via kvm_init_sysreg().
We still have to keep the non-FWB handling stuff in vcpu_reset_hcr().
Also the initialization with HCR_GUEST_FLAGS is kept there but guarded
by !vcpu_has_run_once() to ensure that previous calculated values
don't get overwritten.
While at it rename kvm_init_sysreg() to kvm_calculate_traps() to
better reflect what it's doing.
Signed-off-by: Sebastian Ott <sebott@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_emulate.h | 40 +++++++---------------------
arch/arm64/include/asm/kvm_host.h | 2 +-
arch/arm64/kvm/arm.c | 2 +-
arch/arm64/kvm/sys_regs.c | 34 +++++++++++++++++++++--
4 files changed, 43 insertions(+), 35 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 501e3e019c93..84dc3fac9711 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -69,39 +69,17 @@ static __always_inline bool vcpu_el1_is_32bit(struct kvm_vcpu *vcpu)
static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu)
{
- vcpu->arch.hcr_el2 = HCR_GUEST_FLAGS;
- if (has_vhe() || has_hvhe())
- vcpu->arch.hcr_el2 |= HCR_E2H;
- if (cpus_have_final_cap(ARM64_HAS_RAS_EXTN)) {
- /* route synchronous external abort exceptions to EL2 */
- vcpu->arch.hcr_el2 |= HCR_TEA;
- /* trap error record accesses */
- vcpu->arch.hcr_el2 |= HCR_TERR;
- }
+ if (!vcpu_has_run_once(vcpu))
+ vcpu->arch.hcr_el2 = HCR_GUEST_FLAGS;
Could you give more explaination in your comments about why we still
keep the non-FWB handling in vcpu_reset_hcr()? That would be better for
understanding the special case.
Thanks,
Shaoqin
- if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB)) {
- vcpu->arch.hcr_el2 |= HCR_FWB;
- } else {
- /*
- * For non-FWB CPUs, we trap VM ops (HCR_EL2.TVM) until M+C
- * get set in SCTLR_EL1 such that we can detect when the guest
- * MMU gets turned on and do the necessary cache maintenance
- * then.
- */
+ /*
+ * For non-FWB CPUs, we trap VM ops (HCR_EL2.TVM) until M+C
+ * get set in SCTLR_EL1 such that we can detect when the guest
+ * MMU gets turned on and do the necessary cache maintenance
+ * then.
+ */
+ if (!cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
vcpu->arch.hcr_el2 |= HCR_TVM;
- }
-
- if (cpus_have_final_cap(ARM64_HAS_EVT) &&
- !cpus_have_final_cap(ARM64_MISMATCHED_CACHE_TYPE))
- vcpu->arch.hcr_el2 |= HCR_TID4;
- else
- vcpu->arch.hcr_el2 |= HCR_TID2;
-
- if (vcpu_el1_is_32bit(vcpu))
- vcpu->arch.hcr_el2 &= ~HCR_RW;
-
- if (kvm_has_mte(vcpu->kvm))
- vcpu->arch.hcr_el2 |= HCR_ATA;
}
static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 8170c04fde91..212ae77eefaf 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1122,7 +1122,7 @@ int __init populate_nv_trap_config(void);
bool lock_all_vcpus(struct kvm *kvm);
void unlock_all_vcpus(struct kvm *kvm);
-void kvm_init_sysreg(struct kvm_vcpu *);
+void kvm_calculate_traps(struct kvm_vcpu *);
/* MMIO helpers */
void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 9996a989b52e..6b217afb4e8e 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -797,7 +797,7 @@ int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
* This needs to happen after NV has imposed its own restrictions on
* the feature set
*/
- kvm_init_sysreg(vcpu);
+ kvm_calculate_traps(vcpu);
ret = kvm_timer_enable(vcpu);
if (ret)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 22b45a15d068..41741bf4d2b2 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -4041,11 +4041,33 @@ int kvm_vm_ioctl_get_reg_writable_masks(struct kvm *kvm, struct reg_mask_range *
return 0;
}
-void kvm_init_sysreg(struct kvm_vcpu *vcpu)
+static void vcpu_set_hcr(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = vcpu->kvm;
- mutex_lock(&kvm->arch.config_lock);
+ if (has_vhe() || has_hvhe())
+ vcpu->arch.hcr_el2 |= HCR_E2H;
+ if (cpus_have_final_cap(ARM64_HAS_RAS_EXTN)) {
+ /* route synchronous external abort exceptions to EL2 */
+ vcpu->arch.hcr_el2 |= HCR_TEA;
+ /* trap error record accesses */
+ vcpu->arch.hcr_el2 |= HCR_TERR;
+ }
+
+ if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
+ vcpu->arch.hcr_el2 |= HCR_FWB;
+
+ if (cpus_have_final_cap(ARM64_HAS_EVT) &&
+ !cpus_have_final_cap(ARM64_MISMATCHED_CACHE_TYPE))
+ vcpu->arch.hcr_el2 |= HCR_TID4;
+ else
+ vcpu->arch.hcr_el2 |= HCR_TID2;
+
+ if (vcpu_el1_is_32bit(vcpu))
+ vcpu->arch.hcr_el2 &= ~HCR_RW;
+
+ if (kvm_has_mte(vcpu->kvm))
+ vcpu->arch.hcr_el2 |= HCR_ATA;
/*
* In the absence of FGT, we cannot independently trap TLBI
@@ -4054,6 +4076,14 @@ void kvm_init_sysreg(struct kvm_vcpu *vcpu)
*/
if (!kvm_has_feat(kvm, ID_AA64ISAR0_EL1, TLB, OS))
vcpu->arch.hcr_el2 |= HCR_TTLBOS;
+}
+
+void kvm_calculate_traps(struct kvm_vcpu *vcpu)
+{
+ struct kvm *kvm = vcpu->kvm;
+
+ mutex_lock(&kvm->arch.config_lock);
+ vcpu_set_hcr(vcpu);
if (cpus_have_final_cap(ARM64_HAS_HCX)) {
vcpu->arch.hcrx_el2 = HCRX_GUEST_FLAGS;
--
Shaoqin