[PATCH v4 8/9] RISC-V: KVM: Virtualize per-HART AIA CSRs

Anup Patel
2023-04-04T15:36:38Z

The AIA specification introduce per-HART AIA CSRs which primarily
support:
* 64 local interrupts on both RV64 and RV32
* priority for each of the 64 local interrupts
* interrupt filtering for local interrupts

This patch virtualize above mentioned AIA CSRs and also extend
ONE_REG interface to allow user-space save/restore Guest/VM
view of these CSRs.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
arch/riscv/include/asm/kvm_aia.h | 88 ++++----
arch/riscv/include/uapi/asm/kvm.h | 7 +
arch/riscv/kvm/aia.c | 322 ++++++++++++++++++++++++++++++
3 files changed, 382 insertions(+), 35 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_aia.h b/arch/riscv/include/asm/kvm_aia.h
index 258a835d4c32..1de0717112e5 100644
--- a/arch/riscv/include/asm/kvm_aia.h
+++ b/arch/riscv/include/asm/kvm_aia.h
@@ -12,6 +12,7 @@

#include <linux/jump_label.h>
#include <linux/kvm_types.h>
+#include <asm/csr.h>

struct kvm_aia {
/* In-kernel irqchip created */
@@ -21,7 +22,22 @@ struct kvm_aia {
bool initialized;
};

+struct kvm_vcpu_aia_csr {
+ unsigned long vsiselect;
+ unsigned long hviprio1;
+ unsigned long hviprio2;
+ unsigned long vsieh;
+ unsigned long hviph;
+ unsigned long hviprio1h;
+ unsigned long hviprio2h;
+};
+
struct kvm_vcpu_aia {
+ /* CPU AIA CSR context of Guest VCPU */
+ struct kvm_vcpu_aia_csr guest_csr;
+
+ /* CPU AIA CSR context upon Guest VCPU reset */
+ struct kvm_vcpu_aia_csr guest_reset_csr;
};

#define kvm_riscv_aia_initialized(k) ((k)->arch.aia.initialized)
@@ -32,48 +48,50 @@ DECLARE_STATIC_KEY_FALSE(kvm_riscv_aia_available);
#define kvm_riscv_aia_available() \
static_branch_unlikely(&kvm_riscv_aia_available)

-static inline void kvm_riscv_vcpu_aia_flush_interrupts(struct kvm_vcpu *vcpu)
-{
-}
-
-static inline void kvm_riscv_vcpu_aia_sync_interrupts(struct kvm_vcpu *vcpu)
-{
-}
-
-static inline bool kvm_riscv_vcpu_aia_has_interrupts(struct kvm_vcpu *vcpu,
- u64 mask)
-{
- return false;
-}
-
-static inline void kvm_riscv_vcpu_aia_update_hvip(struct kvm_vcpu *vcpu)
-{
-}
-
-static inline void kvm_riscv_vcpu_aia_load(struct kvm_vcpu *vcpu, int cpu)
-{
-}
-
-static inline void kvm_riscv_vcpu_aia_put(struct kvm_vcpu *vcpu)
+#define KVM_RISCV_AIA_IMSIC_TOPEI (ISELECT_MASK + 1)
+static inline int kvm_riscv_vcpu_aia_imsic_rmw(struct kvm_vcpu *vcpu,
+ unsigned long isel,
+ unsigned long *val,
+ unsigned long new_val,
+ unsigned long wr_mask)
{
+ return 0;
}

-static inline int kvm_riscv_vcpu_aia_get_csr(struct kvm_vcpu *vcpu,
- unsigned long reg_num,
- unsigned long *out_val)
+#ifdef CONFIG_32BIT
+void kvm_riscv_vcpu_aia_flush_interrupts(struct kvm_vcpu *vcpu);
+void kvm_riscv_vcpu_aia_sync_interrupts(struct kvm_vcpu *vcpu);
+#else
+static inline void kvm_riscv_vcpu_aia_flush_interrupts(struct kvm_vcpu *vcpu)
{
- *out_val = 0;
- return 0;
}
-
-static inline int kvm_riscv_vcpu_aia_set_csr(struct kvm_vcpu *vcpu,
- unsigned long reg_num,
- unsigned long val)
+static inline void kvm_riscv_vcpu_aia_sync_interrupts(struct kvm_vcpu *vcpu)
{
- return 0;
}
-
-#define KVM_RISCV_VCPU_AIA_CSR_FUNCS
+#endif
+bool kvm_riscv_vcpu_aia_has_interrupts(struct kvm_vcpu *vcpu, u64 mask);
+
+void kvm_riscv_vcpu_aia_update_hvip(struct kvm_vcpu *vcpu);
+void kvm_riscv_vcpu_aia_load(struct kvm_vcpu *vcpu, int cpu);
+void kvm_riscv_vcpu_aia_put(struct kvm_vcpu *vcpu);
+int kvm_riscv_vcpu_aia_get_csr(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long *out_val);
+int kvm_riscv_vcpu_aia_set_csr(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long val);
+
+int kvm_riscv_vcpu_aia_rmw_topei(struct kvm_vcpu *vcpu,
+ unsigned int csr_num,
+ unsigned long *val,
+ unsigned long new_val,
+ unsigned long wr_mask);
+int kvm_riscv_vcpu_aia_rmw_ireg(struct kvm_vcpu *vcpu, unsigned int csr_num,
+ unsigned long *val, unsigned long new_val,
+ unsigned long wr_mask);
+#define KVM_RISCV_VCPU_AIA_CSR_FUNCS \
+{ .base = CSR_SIREG, .count = 1, .func = kvm_riscv_vcpu_aia_rmw_ireg }, \
+{ .base = CSR_STOPEI, .count = 1, .func = kvm_riscv_vcpu_aia_rmw_topei },

static inline int kvm_riscv_vcpu_aia_update(struct kvm_vcpu *vcpu)
{
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index cbc3e74fa670..c517e70ddcd6 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -81,6 +81,13 @@ struct kvm_riscv_csr {

/* AIA CSR registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
struct kvm_riscv_aia_csr {
+ unsigned long siselect;
+ unsigned long siprio1;
+ unsigned long siprio2;
+ unsigned long sieh;
+ unsigned long siph;
+ unsigned long siprio1h;
+ unsigned long siprio2h;
};

/* TIMER registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
diff --git a/arch/riscv/kvm/aia.c b/arch/riscv/kvm/aia.c
index 7a633331cd3e..4bf1e83add55 100644
--- a/arch/riscv/kvm/aia.c
+++ b/arch/riscv/kvm/aia.c
@@ -7,6 +7,7 @@
* Anup Patel <apatel@ventanamicro.com>
*/

+#include <linux/kernel.h>
#include <linux/kvm_host.h>
#include <asm/hwcap.h>

@@ -26,6 +27,327 @@ static void aia_set_hvictl(bool ext_irq_pending)
csr_write(CSR_HVICTL, hvictl);
}

+#ifdef CONFIG_32BIT
+void kvm_riscv_vcpu_aia_flush_interrupts(struct kvm_vcpu *vcpu)
+{
+ struct kvm_vcpu_aia_csr *csr = &vcpu->arch.aia_context.guest_csr;
+ unsigned long mask, val;
+
+ if (!kvm_riscv_aia_available())
+ return;
+
+ if (READ_ONCE(vcpu->arch.irqs_pending_mask[1])) {
+ mask = xchg_acquire(&vcpu->arch.irqs_pending_mask[1], 0);
+ val = READ_ONCE(vcpu->arch.irqs_pending[1]) & mask;
+
+ csr->hviph &= ~mask;
+ csr->hviph |= val;
+ }
+}
+
+void kvm_riscv_vcpu_aia_sync_interrupts(struct kvm_vcpu *vcpu)
+{
+ struct kvm_vcpu_aia_csr *csr = &vcpu->arch.aia_context.guest_csr;
+
+ if (kvm_riscv_aia_available())
+ csr->vsieh = csr_read(CSR_VSIEH);
+}
+#endif
+
+bool kvm_riscv_vcpu_aia_has_interrupts(struct kvm_vcpu *vcpu, u64 mask)
+{
+ unsigned long seip;
+
+ if (!kvm_riscv_aia_available())
+ return false;
+
+#ifdef CONFIG_32BIT
+ if (READ_ONCE(vcpu->arch.irqs_pending[1]) &
+ (vcpu->arch.aia_context.guest_csr.vsieh & upper_32_bits(mask))
+ return true;
+#endif
+
+ seip = vcpu->arch.guest_csr.vsie;
+ seip &= (unsigned long)mask;
+ seip &= BIT(IRQ_S_EXT);
+
+ if (!kvm_riscv_aia_initialized(vcpu->kvm) || !seip)
+ return false;
+
+ return false;
+}
+
+void kvm_riscv_vcpu_aia_update_hvip(struct kvm_vcpu *vcpu)
+{
+ struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+ if (!kvm_riscv_aia_available())
+ return;
+
+#ifdef CONFIG_32BIT
+ csr_write(CSR_HVIPH, vcpu->arch.aia_context.guest_csr.hviph);
+#endif
+ aia_set_hvictl(!!(csr->hvip & BIT(IRQ_VS_EXT)));
+}
+
+void kvm_riscv_vcpu_aia_load(struct kvm_vcpu *vcpu, int cpu)
+{
+ struct kvm_vcpu_aia_csr *csr = &vcpu->arch.aia_context.guest_csr;
+
+ if (!kvm_riscv_aia_available())
+ return;
+
+ csr_write(CSR_VSISELECT, csr->vsiselect);
+ csr_write(CSR_HVIPRIO1, csr->hviprio1);
+ csr_write(CSR_HVIPRIO2, csr->hviprio2);
+#ifdef CONFIG_32BIT
+ csr_write(CSR_VSIEH, csr->vsieh);
+ csr_write(CSR_HVIPH, csr->hviph);
+ csr_write(CSR_HVIPRIO1H, csr->hviprio1h);
+ csr_write(CSR_HVIPRIO2H, csr->hviprio2h);
+#endif
+}
+
+void kvm_riscv_vcpu_aia_put(struct kvm_vcpu *vcpu)
+{
+ struct kvm_vcpu_aia_csr *csr = &vcpu->arch.aia_context.guest_csr;
+
+ if (!kvm_riscv_aia_available())
+ return;
+
+ csr->vsiselect = csr_read(CSR_VSISELECT);
+ csr->hviprio1 = csr_read(CSR_HVIPRIO1);
+ csr->hviprio2 = csr_read(CSR_HVIPRIO2);
+#ifdef CONFIG_32BIT
+ csr->vsieh = csr_read(CSR_VSIEH);
+ csr->hviph = csr_read(CSR_HVIPH);
+ csr->hviprio1h = csr_read(CSR_HVIPRIO1H);
+ csr->hviprio2h = csr_read(CSR_HVIPRIO2H);
+#endif
+}
+
+int kvm_riscv_vcpu_aia_get_csr(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long *out_val)
+{
+ struct kvm_vcpu_aia_csr *csr = &vcpu->arch.aia_context.guest_csr;
+
+ if (reg_num >= sizeof(struct kvm_riscv_aia_csr) / sizeof(unsigned long))
+ return -EINVAL;
+
+ *out_val = 0;
+ if (kvm_riscv_aia_available())
+ *out_val = ((unsigned long *)csr)[reg_num];
+
+ return 0;
+}
+
+int kvm_riscv_vcpu_aia_set_csr(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long val)
+{
+ struct kvm_vcpu_aia_csr *csr = &vcpu->arch.aia_context.guest_csr;
+
+ if (reg_num >= sizeof(struct kvm_riscv_aia_csr) / sizeof(unsigned long))
+ return -EINVAL;
+
+ if (kvm_riscv_aia_available()) {
+ ((unsigned long *)csr)[reg_num] = val;
+
+#ifdef CONFIG_32BIT
+ if (reg_num == KVM_REG_RISCV_CSR_AIA_REG(siph))
+ WRITE_ONCE(vcpu->arch.irqs_pending_mask[1], 0);
+#endif
+ }
+
+ return 0;
+}
+
+int kvm_riscv_vcpu_aia_rmw_topei(struct kvm_vcpu *vcpu,
+ unsigned int csr_num,
+ unsigned long *val,
+ unsigned long new_val,
+ unsigned long wr_mask)
+{
+ /* If AIA not available then redirect trap */
+ if (!kvm_riscv_aia_available())
+ return KVM_INSN_ILLEGAL_TRAP;
+
+ /* If AIA not initialized then forward to user space */
+ if (!kvm_riscv_aia_initialized(vcpu->kvm))
+ return KVM_INSN_EXIT_TO_USER_SPACE;
+
+ return kvm_riscv_vcpu_aia_imsic_rmw(vcpu, KVM_RISCV_AIA_IMSIC_TOPEI,
+ val, new_val, wr_mask);
+}
+
+/*
+ * External IRQ priority always read-only zero. This means default
+ * priority order is always preferred for external IRQs unless
+ * HVICTL.IID == 9 and HVICTL.IPRIO != 0
+ */
+static int aia_irq2bitpos[] = {
+0, 8, -1, -1, 16, 24, -1, -1, /* 0 - 7 */
+32, -1, -1, -1, -1, 40, 48, 56, /* 8 - 15 */
+64, 72, 80, 88, 96, 104, 112, 120, /* 16 - 23 */
+-1, -1, -1, -1, -1, -1, -1, -1, /* 24 - 31 */
+-1, -1, -1, -1, -1, -1, -1, -1, /* 32 - 39 */
+-1, -1, -1, -1, -1, -1, -1, -1, /* 40 - 47 */
+-1, -1, -1, -1, -1, -1, -1, -1, /* 48 - 55 */
+-1, -1, -1, -1, -1, -1, -1, -1, /* 56 - 63 */
+};
+
+static u8 aia_get_iprio8(struct kvm_vcpu *vcpu, unsigned int irq)
+{
+ unsigned long hviprio;
+ int bitpos = aia_irq2bitpos[irq];
+
+ if (bitpos < 0)
+ return 0;
+
+ switch (bitpos / BITS_PER_LONG) {
+ case 0:
+ hviprio = csr_read(CSR_HVIPRIO1);
+ break;
+ case 1:
+#ifndef CONFIG_32BIT
+ hviprio = csr_read(CSR_HVIPRIO2);
+ break;
+#else
+ hviprio = csr_read(CSR_HVIPRIO1H);
+ break;
+ case 2:
+ hviprio = csr_read(CSR_HVIPRIO2);
+ break;
+ case 3:
+ hviprio = csr_read(CSR_HVIPRIO2H);
+ break;
+#endif
+ default:
+ return 0;
+ }
+
+ return (hviprio >> (bitpos % BITS_PER_LONG)) & TOPI_IPRIO_MASK;
+}
+
+static void aia_set_iprio8(struct kvm_vcpu *vcpu, unsigned int irq, u8 prio)
+{
+ unsigned long hviprio;
+ int bitpos = aia_irq2bitpos[irq];
+
+ if (bitpos < 0)
+ return;
+
+ switch (bitpos / BITS_PER_LONG) {
+ case 0:
+ hviprio = csr_read(CSR_HVIPRIO1);
+ break;
+ case 1:
+#ifndef CONFIG_32BIT
+ hviprio = csr_read(CSR_HVIPRIO2);
+ break;
+#else
+ hviprio = csr_read(CSR_HVIPRIO1H);
+ break;
+ case 2:
+ hviprio = csr_read(CSR_HVIPRIO2);
+ break;
+ case 3:
+ hviprio = csr_read(CSR_HVIPRIO2H);
+ break;
+#endif
+ default:
+ return;
+ }
+
+ hviprio &= ~(TOPI_IPRIO_MASK << (bitpos % BITS_PER_LONG));
+ hviprio |= (unsigned long)prio << (bitpos % BITS_PER_LONG);
+
+ switch (bitpos / BITS_PER_LONG) {
+ case 0:
+ csr_write(CSR_HVIPRIO1, hviprio);
+ break;
+ case 1:
+#ifndef CONFIG_32BIT
+ csr_write(CSR_HVIPRIO2, hviprio);
+ break;
+#else
+ csr_write(CSR_HVIPRIO1H, hviprio);
+ break;
+ case 2:
+ csr_write(CSR_HVIPRIO2, hviprio);
+ break;
+ case 3:
+ csr_write(CSR_HVIPRIO2H, hviprio);
+ break;
+#endif
+ default:
+ return;
+ }
+}
+
+static int aia_rmw_iprio(struct kvm_vcpu *vcpu, unsigned int isel,
+ unsigned long *val, unsigned long new_val,
+ unsigned long wr_mask)
+{
+ int i, first_irq, nirqs;
+ unsigned long old_val;
+ u8 prio;
+
+#ifndef CONFIG_32BIT
+ if (isel & 0x1)
+ return KVM_INSN_ILLEGAL_TRAP;
+#endif
+
+ nirqs = 4 * (BITS_PER_LONG / 32);
+ first_irq = (isel - ISELECT_IPRIO0) * 4;
+
+ old_val = 0;
+ for (i = 0; i < nirqs; i++) {
+ prio = aia_get_iprio8(vcpu, first_irq + i);
+ old_val |= (unsigned long)prio << (TOPI_IPRIO_BITS * i);
+ }
+
+ if (val)
+ *val = old_val;
+
+ if (wr_mask) {
+ new_val = (old_val & ~wr_mask) | (new_val & wr_mask);
+ for (i = 0; i < nirqs; i++) {
+ prio = (new_val >> (TOPI_IPRIO_BITS * i)) &
+ TOPI_IPRIO_MASK;
+ aia_set_iprio8(vcpu, first_irq + i, prio);
+ }
+ }
+
+ return KVM_INSN_CONTINUE_NEXT_SEPC;
+}
+
+#define IMSIC_FIRST 0x70
+#define IMSIC_LAST 0xff
+int kvm_riscv_vcpu_aia_rmw_ireg(struct kvm_vcpu *vcpu, unsigned int csr_num,
+ unsigned long *val, unsigned long new_val,
+ unsigned long wr_mask)
+{
+ unsigned int isel;
+
+ /* If AIA not available then redirect trap */
+ if (!kvm_riscv_aia_available())
+ return KVM_INSN_ILLEGAL_TRAP;
+
+ /* First try to emulate in kernel space */
+ isel = csr_read(CSR_VSISELECT) & ISELECT_MASK;
+ if (isel >= ISELECT_IPRIO0 && isel <= ISELECT_IPRIO15)
+ return aia_rmw_iprio(vcpu, isel, val, new_val, wr_mask);
+ else if (isel >= IMSIC_FIRST && isel <= IMSIC_LAST &&
+ kvm_riscv_aia_initialized(vcpu->kvm))
+ return kvm_riscv_vcpu_aia_imsic_rmw(vcpu, isel, val, new_val,
+ wr_mask);
+
+ /* We can't handle it here so redirect to user space */
+ return KVM_INSN_EXIT_TO_USER_SPACE;
+}
+
void kvm_riscv_aia_enable(void)
{
if (!kvm_riscv_aia_available())
--
2.34.1