RISC-V: KVM: Implement kvm_arch_vcpu_ioctl_set_guest_debug()

kvm_vm_ioctl_check_extension(): Return 1 if KVM_CAP_SET_GUEST_DEBUG is
been checked.

kvm_arch_vcpu_ioctl_set_guest_debug(): Update the guest_debug flags
from userspace accordingly. Route the breakpoint exceptions to HS mode
if the VCPU is being debugged by userspace, by clearing the
corresponding bit in hedeleg.

Initialize the hedeleg configuration in kvm_riscv_vcpu_setup_config().
Write the actual CSR in kvm_arch_vcpu_load().

Signed-off-by: Chao Du <duchao@eswincomputing.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20240402062628.5425-2-duchao@eswincomputing.com
Signed-off-by: Anup Patel <anup@brainfault.org>

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 484d04a92fa6b7f02a5ef0b24faee9a87f98b1bb..da4ab7e175ff04d5ac0431ae01eb4bdc1801788e 100644 (file)
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -43,6 +43,17 @@
        KVM_ARCH_REQ_FLAGS(5, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
 #define KVM_REQ_STEAL_UPDATE           KVM_ARCH_REQ(6)
 
+#define KVM_HEDELEG_DEFAULT            (BIT(EXC_INST_MISALIGNED) | \
+                                        BIT(EXC_BREAKPOINT)      | \
+                                        BIT(EXC_SYSCALL)         | \
+                                        BIT(EXC_INST_PAGE_FAULT) | \
+                                        BIT(EXC_LOAD_PAGE_FAULT) | \
+                                        BIT(EXC_STORE_PAGE_FAULT))
+
+#define KVM_HIDELEG_DEFAULT            (BIT(IRQ_VS_SOFT)  | \
+                                        BIT(IRQ_VS_TIMER) | \
+                                        BIT(IRQ_VS_EXT))
+
 enum kvm_riscv_hfence_type {
        KVM_RISCV_HFENCE_UNKNOWN = 0,
        KVM_RISCV_HFENCE_GVMA_VMID_GPA,
@@ -169,6 +180,7 @@ struct kvm_vcpu_csr {
 struct kvm_vcpu_config {
        u64 henvcfg;
        u64 hstateen0;
+       unsigned long hedeleg;
 };
 
 struct kvm_vcpu_smstateen_csr {

diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index 225a435d9c9a9c25b8cf24f4501a2e9e3bb94d1b..bab2ec34cd87667d5a9814904b8ca5b3fd1c36c1 100644 (file)
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c
@@ -22,22 +22,8 @@ long kvm_arch_dev_ioctl(struct file *filp,
 
 int kvm_arch_hardware_enable(void)
 {
-       unsigned long hideleg, hedeleg;
-
-       hedeleg = 0;
-       hedeleg |= (1UL << EXC_INST_MISALIGNED);
-       hedeleg |= (1UL << EXC_BREAKPOINT);
-       hedeleg |= (1UL << EXC_SYSCALL);
-       hedeleg |= (1UL << EXC_INST_PAGE_FAULT);
-       hedeleg |= (1UL << EXC_LOAD_PAGE_FAULT);
-       hedeleg |= (1UL << EXC_STORE_PAGE_FAULT);
-       csr_write(CSR_HEDELEG, hedeleg);
-
-       hideleg = 0;
-       hideleg |= (1UL << IRQ_VS_SOFT);
-       hideleg |= (1UL << IRQ_VS_TIMER);
-       hideleg |= (1UL << IRQ_VS_EXT);
-       csr_write(CSR_HIDELEG, hideleg);
+       csr_write(CSR_HEDELEG, KVM_HEDELEG_DEFAULT);
+       csr_write(CSR_HIDELEG, KVM_HIDELEG_DEFAULT);
 
        /* VS should access only the time counter directly. Everything else should trap */
        csr_write(CSR_HCOUNTEREN, 0x02);

diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index b5ca9f2e98acd216caf4dd7537d106ce4f5bcdc0..f3c87f0c93ba47b83c8a7413d23c2417f444e49b 100644 (file)
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -475,8 +475,15 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
                                        struct kvm_guest_debug *dbg)
 {
-       /* TODO; To be implemented later. */
-       return -EINVAL;
+       if (dbg->control & KVM_GUESTDBG_ENABLE) {
+               vcpu->guest_debug = dbg->control;
+               vcpu->arch.cfg.hedeleg &= ~BIT(EXC_BREAKPOINT);
+       } else {
+               vcpu->guest_debug = 0;
+               vcpu->arch.cfg.hedeleg |= BIT(EXC_BREAKPOINT);
+       }
+
+       return 0;
 }
 
 static void kvm_riscv_vcpu_setup_config(struct kvm_vcpu *vcpu)
@@ -505,6 +512,10 @@ static void kvm_riscv_vcpu_setup_config(struct kvm_vcpu *vcpu)
                if (riscv_isa_extension_available(isa, SMSTATEEN))
                        cfg->hstateen0 |= SMSTATEEN0_SSTATEEN0;
        }
+
+       cfg->hedeleg = KVM_HEDELEG_DEFAULT;
+       if (vcpu->guest_debug)
+               cfg->hedeleg &= ~BIT(EXC_BREAKPOINT);
 }
 
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
@@ -519,6 +530,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
        csr_write(CSR_VSEPC, csr->vsepc);
        csr_write(CSR_VSCAUSE, csr->vscause);
        csr_write(CSR_VSTVAL, csr->vstval);
+       csr_write(CSR_HEDELEG, cfg->hedeleg);
        csr_write(CSR_HVIP, csr->hvip);
        csr_write(CSR_VSATP, csr->vsatp);
        csr_write(CSR_HENVCFG, cfg->henvcfg);

diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index ce58bc48e5b87b44c24d09d0a3f4a987f88207c0..7396b8654f454bd3ce49e0ab403d672ad0227d4b 100644 (file)
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -186,6 +186,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
        case KVM_CAP_READONLY_MEM:
        case KVM_CAP_MP_STATE:
        case KVM_CAP_IMMEDIATE_EXIT:
+       case KVM_CAP_SET_GUEST_DEBUG:
                r = 1;
                break;
        case KVM_CAP_NR_VCPUS: