Subject: [PATCH v4 07/66] KVM: arm64: nv: Handle HCR_EL2.NV system register traps

From: Marc Zyngier <[email-masked]>
Date: Mon, 10 May 2021 17:58:21 +0100

From: Jintack Lim <[email-masked]>

ARM v8.3 introduces a new bit in the HCR_EL2, which is the NV bit. When
this bit is set, accessing EL2 registers in EL1 traps to EL2. In
addition, executing the following instructions in EL1 will trap to EL2:
tlbi, at, eret, and msr/mrs instructions to access SP_EL1. Most of the
instructions that trap to EL2 with the NV bit were undef at EL1 prior to
ARM v8.3. The only instruction that was not undef is eret.

This patch sets up a handler for EL2 registers and SP_EL1 register
accesses at EL1. The host hypervisor keeps those register values in
memory, and will emulate their behavior.

This patch doesn't set the NV bit yet. It will be set in a later patch
once nested virtualization support is completed.

Signed-off-by: Jintack Lim <[email-masked]>
[maz: added SCTLR_EL2 RES0/RES1 handling]
Signed-off-by: Marc Zyngier <[email-masked]>
---
 arch/arm64/include/asm/sysreg.h |  41 +++++++++++-
 arch/arm64/kvm/sys_regs.c       | 109 ++++++++++++++++++++++++++++++--
 2 files changed, 144 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 65d15700a168..10c0d3a476e2 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -525,10 +525,26 @@
 
 #define SYS_PMCCFILTR_EL0		sys_reg(3, 3, 14, 15, 7)
 
+#define SYS_VPIDR_EL2			sys_reg(3, 4, 0, 0, 0)
+#define SYS_VMPIDR_EL2			sys_reg(3, 4, 0, 0, 5)
+
 #define SYS_SCTLR_EL2			sys_reg(3, 4, 1, 0, 0)
+#define SYS_ACTLR_EL2			sys_reg(3, 4, 1, 0, 1)
+#define SYS_HCR_EL2			sys_reg(3, 4, 1, 1, 0)
+#define SYS_MDCR_EL2			sys_reg(3, 4, 1, 1, 1)
+#define SYS_CPTR_EL2			sys_reg(3, 4, 1, 1, 2)
+#define SYS_HSTR_EL2			sys_reg(3, 4, 1, 1, 3)
 #define SYS_HFGRTR_EL2			sys_reg(3, 4, 1, 1, 4)
 #define SYS_HFGWTR_EL2			sys_reg(3, 4, 1, 1, 5)
 #define SYS_HFGITR_EL2			sys_reg(3, 4, 1, 1, 6)
+#define SYS_HACR_EL2			sys_reg(3, 4, 1, 1, 7)
+
+#define SYS_TTBR0_EL2			sys_reg(3, 4, 2, 0, 0)
+#define SYS_TTBR1_EL2			sys_reg(3, 4, 2, 0, 1)
+#define SYS_TCR_EL2			sys_reg(3, 4, 2, 0, 2)
+#define SYS_VTTBR_EL2			sys_reg(3, 4, 2, 1, 0)
+#define SYS_VTCR_EL2			sys_reg(3, 4, 2, 1, 2)
+
 #define SYS_ZCR_EL2			sys_reg(3, 4, 1, 2, 0)
 #define SYS_TRFCR_EL2			sys_reg(3, 4, 1, 2, 1)
 #define SYS_DACR32_EL2			sys_reg(3, 4, 3, 0, 0)
@@ -537,14 +553,26 @@
 #define SYS_HAFGRTR_EL2			sys_reg(3, 4, 3, 1, 6)
 #define SYS_SPSR_EL2			sys_reg(3, 4, 4, 0, 0)
 #define SYS_ELR_EL2			sys_reg(3, 4, 4, 0, 1)
+#define SYS_SP_EL1			sys_reg(3, 4, 4, 1, 0)
 #define SYS_IFSR32_EL2			sys_reg(3, 4, 5, 0, 1)
+#define SYS_AFSR0_EL2			sys_reg(3, 4, 5, 1, 0)
+#define SYS_AFSR1_EL2			sys_reg(3, 4, 5, 1, 1)
 #define SYS_ESR_EL2			sys_reg(3, 4, 5, 2, 0)
 #define SYS_VSESR_EL2			sys_reg(3, 4, 5, 2, 3)
 #define SYS_FPEXC32_EL2			sys_reg(3, 4, 5, 3, 0)
 #define SYS_TFSR_EL2			sys_reg(3, 4, 5, 6, 0)
 #define SYS_FAR_EL2			sys_reg(3, 4, 6, 0, 0)
 
-#define SYS_VDISR_EL2			sys_reg(3, 4, 12, 1,  1)
+#define SYS_FAR_EL2			sys_reg(3, 4, 6, 0, 0)
+#define SYS_HPFAR_EL2			sys_reg(3, 4, 6, 0, 4)
+
+#define SYS_MAIR_EL2			sys_reg(3, 4, 10, 2, 0)
+#define SYS_AMAIR_EL2			sys_reg(3, 4, 10, 3, 0)
+
+#define SYS_VBAR_EL2			sys_reg(3, 4, 12, 0, 0)
+#define SYS_RVBAR_EL2			sys_reg(3, 4, 12, 0, 1)
+#define SYS_RMR_EL2			sys_reg(3, 4, 12, 0, 2)
+#define SYS_VDISR_EL2			sys_reg(3, 4, 12, 1, 1)
 #define __SYS__AP0Rx_EL2(x)		sys_reg(3, 4, 12, 8, x)
 #define SYS_ICH_AP0R0_EL2		__SYS__AP0Rx_EL2(0)
 #define SYS_ICH_AP0R1_EL2		__SYS__AP0Rx_EL2(1)
@@ -586,15 +614,24 @@
 #define SYS_ICH_LR14_EL2		__SYS__LR8_EL2(6)
 #define SYS_ICH_LR15_EL2		__SYS__LR8_EL2(7)
 
+#define SYS_CONTEXTIDR_EL2		sys_reg(3, 4, 13, 0, 1)
+#define SYS_TPIDR_EL2			sys_reg(3, 4, 13, 0, 2)
+
+#define SYS_CNTVOFF_EL2			sys_reg(3, 4, 14, 0, 3)
+#define SYS_CNTHCTL_EL2			sys_reg(3, 4, 14, 1, 0)
+
 /* VHE encodings for architectural EL0/1 system registers */
 #define SYS_SCTLR_EL12			sys_reg(3, 5, 1, 0, 0)
 #define SYS_CPACR_EL12			sys_reg(3, 5, 1, 0, 2)
 #define SYS_ZCR_EL12			sys_reg(3, 5, 1, 2, 0)
+
 #define SYS_TTBR0_EL12			sys_reg(3, 5, 2, 0, 0)
 #define SYS_TTBR1_EL12			sys_reg(3, 5, 2, 0, 1)
 #define SYS_TCR_EL12			sys_reg(3, 5, 2, 0, 2)
+
 #define SYS_SPSR_EL12			sys_reg(3, 5, 4, 0, 0)
 #define SYS_ELR_EL12			sys_reg(3, 5, 4, 0, 1)
+
 #define SYS_AFSR0_EL12			sys_reg(3, 5, 5, 1, 0)
 #define SYS_AFSR1_EL12			sys_reg(3, 5, 5, 1, 1)
 #define SYS_ESR_EL12			sys_reg(3, 5, 5, 2, 0)
@@ -612,6 +649,8 @@
 #define SYS_CNTV_CTL_EL02		sys_reg(3, 5, 14, 3, 1)
 #define SYS_CNTV_CVAL_EL02		sys_reg(3, 5, 14, 3, 2)
 
+#define SYS_SP_EL2			sys_reg(3, 6,  4, 1, 0)
+
 /* Common SCTLR_ELx flags. */
 #define SCTLR_ELx_DSSBS	(BIT(44))
 #define SCTLR_ELx_ATA	(BIT(43))
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 76ea2800c33e..68266eb139b7 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -109,6 +109,46 @@ static u32 get_ccsidr(u32 csselr)
 	return ccsidr;
 }
 
+static bool access_rw(struct kvm_vcpu *vcpu,
+		      struct sys_reg_params *p,
+		      const struct sys_reg_desc *r)
+{
+	if (p->is_write)
+		vcpu_write_sys_reg(vcpu, p->regval, r->reg);
+	else
+		p->regval = vcpu_read_sys_reg(vcpu, r->reg);
+
+	return true;
+}
+
+static bool access_sctlr_el2(struct kvm_vcpu *vcpu,
+			     struct sys_reg_params *p,
+			     const struct sys_reg_desc *r)
+{
+	if (p->is_write) {
+		u64 val = p->regval;
+
+		if (vcpu_el2_e2h_is_set(vcpu) && vcpu_el2_tge_is_set(vcpu)) {
+			val &= ~(GENMASK_ULL(63,45) | GENMASK_ULL(34, 32) |
+				 BIT_ULL(17) | BIT_ULL(9));
+			val |=  SCTLR_EL1_RES1;
+		} else {
+			val &= ~(GENMASK_ULL(63,45) | BIT_ULL(42) |
+				 GENMASK_ULL(39, 38) | GENMASK_ULL(35, 32) |
+				 BIT_ULL(26) | BIT_ULL(24) | BIT_ULL(20) |
+				 BIT_ULL(17) | GENMASK_ULL(15, 14) |
+				 GENMASK(10, 7));
+			val |=  SCTLR_EL2_RES1;
+		}
+
+		vcpu_write_sys_reg(vcpu, val, r->reg);
+	} else {
+		p->regval = vcpu_read_sys_reg(vcpu, r->reg);
+	}
+
+	return true;
+}
+
 /*
  * See note at ARMv7 ARM B1.14.4 (TL;DR: S/W ops are not easily virtualized).
  */
@@ -267,6 +307,14 @@ static bool trap_raz_wi(struct kvm_vcpu *vcpu,
 		return read_zero(vcpu, p);
 }
 
+static bool trap_undef(struct kvm_vcpu *vcpu,
+		       struct sys_reg_params *p,
+		       const struct sys_reg_desc *r)
+{
+	kvm_inject_undefined(vcpu);
+	return false;
+}
+
 /*
  * ARMv8.1 mandates at least a trivial LORegion implementation, where all the
  * RW registers are RES0 (which we can implement as RAZ/WI). On an ARMv8.0
@@ -346,12 +394,9 @@ static bool trap_debug_regs(struct kvm_vcpu *vcpu,
 			    struct sys_reg_params *p,
 			    const struct sys_reg_desc *r)
 {
-	if (p->is_write) {
-		vcpu_write_sys_reg(vcpu, p->regval, r->reg);
+	access_rw(vcpu, p, r);
+	if (p->is_write)
 		vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY;
-	} else {
-		p->regval = vcpu_read_sys_reg(vcpu, r->reg);
-	}
 
 	trace_trap_reg(__func__, r->reg, p->is_write, p->regval);
 
@@ -1335,6 +1380,18 @@ static bool access_ccsidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 	.set_user = set_raz_id_reg,		\
 }
 
+static bool access_sp_el1(struct kvm_vcpu *vcpu,
+			  struct sys_reg_params *p,
+			  const struct sys_reg_desc *r)
+{
+	if (p->is_write)
+		__vcpu_sys_reg(vcpu, SP_EL1) = p->regval;
+	else
+		p->regval = __vcpu_sys_reg(vcpu, SP_EL1);
+
+	return true;
+}
+
 /*
  * Architected system registers.
  * Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2
@@ -1744,9 +1801,51 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	{ PMU_SYS_REG(SYS_PMCCFILTR_EL0), .access = access_pmu_evtyper,
 	  .reset = reset_val, .reg = PMCCFILTR_EL0, .val = 0 },
 
+	{ SYS_DESC(SYS_VPIDR_EL2), access_rw, reset_val, VPIDR_EL2, 0 },
+	{ SYS_DESC(SYS_VMPIDR_EL2), access_rw, reset_val, VMPIDR_EL2, 0 },
+
+	{ SYS_DESC(SYS_SCTLR_EL2), access_sctlr_el2, reset_val, SCTLR_EL2, SCTLR_EL2_RES1 },
+	{ SYS_DESC(SYS_ACTLR_EL2), access_rw, reset_val, ACTLR_EL2, 0 },
+	{ SYS_DESC(SYS_HCR_EL2), access_rw, reset_val, HCR_EL2, 0 },
+	{ SYS_DESC(SYS_MDCR_EL2), access_rw, reset_val, MDCR_EL2, 0 },
+	{ SYS_DESC(SYS_CPTR_EL2), access_rw, reset_val, CPTR_EL2, CPTR_EL2_RES1 },
+	{ SYS_DESC(SYS_HSTR_EL2), access_rw, reset_val, HSTR_EL2, 0 },
+	{ SYS_DESC(SYS_HACR_EL2), access_rw, reset_val, HACR_EL2, 0 },
+
+	{ SYS_DESC(SYS_TTBR0_EL2), access_rw, reset_val, TTBR0_EL2, 0 },
+	{ SYS_DESC(SYS_TTBR1_EL2), access_rw, reset_val, TTBR1_EL2, 0 },
+	{ SYS_DESC(SYS_TCR_EL2), access_rw, reset_val, TCR_EL2, TCR_EL2_RES1 },
+	{ SYS_DESC(SYS_VTTBR_EL2), access_rw, reset_val, VTTBR_EL2, 0 },
+	{ SYS_DESC(SYS_VTCR_EL2), access_rw, reset_val, VTCR_EL2, 0 },
+
 	{ SYS_DESC(SYS_DACR32_EL2), NULL, reset_unknown, DACR32_EL2 },
+	{ SYS_DESC(SYS_SPSR_EL2), access_rw, reset_val, SPSR_EL2, 0 },
+	{ SYS_DESC(SYS_ELR_EL2), access_rw, reset_val, ELR_EL2, 0 },
+	{ SYS_DESC(SYS_SP_EL1), access_sp_el1},
+
 	{ SYS_DESC(SYS_IFSR32_EL2), NULL, reset_unknown, IFSR32_EL2 },
+	{ SYS_DESC(SYS_AFSR0_EL2), access_rw, reset_val, AFSR0_EL2, 0 },
+	{ SYS_DESC(SYS_AFSR1_EL2), access_rw, reset_val, AFSR1_EL2, 0 },
+	{ SYS_DESC(SYS_ESR_EL2), access_rw, reset_val, ESR_EL2, 0 },
 	{ SYS_DESC(SYS_FPEXC32_EL2), NULL, reset_val, FPEXC32_EL2, 0x700 },
+
+	{ SYS_DESC(SYS_FAR_EL2), access_rw, reset_val, FAR_EL2, 0 },
+	{ SYS_DESC(SYS_HPFAR_EL2), access_rw, reset_val, HPFAR_EL2, 0 },
+
+	{ SYS_DESC(SYS_MAIR_EL2), access_rw, reset_val, MAIR_EL2, 0 },
+	{ SYS_DESC(SYS_AMAIR_EL2), access_rw, reset_val, AMAIR_EL2, 0 },
+
+	{ SYS_DESC(SYS_VBAR_EL2), access_rw, reset_val, VBAR_EL2, 0 },
+	{ SYS_DESC(SYS_RVBAR_EL2), access_rw, reset_val, RVBAR_EL2, 0 },
+	{ SYS_DESC(SYS_RMR_EL2), trap_undef },
+
+	{ SYS_DESC(SYS_CONTEXTIDR_EL2), access_rw, reset_val, CONTEXTIDR_EL2, 0 },
+	{ SYS_DESC(SYS_TPIDR_EL2), access_rw, reset_val, TPIDR_EL2, 0 },
+
+	{ SYS_DESC(SYS_CNTVOFF_EL2), access_rw, reset_val, CNTVOFF_EL2, 0 },
+	{ SYS_DESC(SYS_CNTHCTL_EL2), access_rw, reset_val, CNTHCTL_EL2, 0 },
+
+	{ SYS_DESC(SYS_SP_EL2), NULL, reset_unknown, SP_EL2 },
 };
 
 static bool trap_dbgdidr(struct kvm_vcpu *vcpu,
-- 
2.29.2

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