[RFC PATCH v2 28/38] KVM: arm64: Emulate EL12 register accesses from the virtual EL2

Jintack Lim
2017-07-18T16:58:54Z

With HCR_EL2.NV bit set, accesses to EL12 registers in the virtual EL2
trap to EL2. Handle those traps just like we do for EL1 registers.

One exception is CNTKCTL_EL12. We don't trap on CNTKCTL_EL1 for non-VHE
virtual EL2 because we don't have to. However, accessing CNTKCTL_EL12
will trap since it's one of the EL12 registers controlled by HCR_EL2.NV
bit. Therefore, add a handler for it and don't treat it as a
non-trap-registers when preparing a shadow context.

Move EL12 system register macros to a common place to reuse them.

Signed-off-by: Jintack Lim <jintack.lim@linaro.org>
---
arch/arm64/include/asm/kvm_hyp.h | 24 ------------------------
arch/arm64/include/asm/sysreg.h | 24 ++++++++++++++++++++++++
arch/arm64/kvm/context.c | 7 +++++++
arch/arm64/kvm/sys_regs.c | 25 +++++++++++++++++++++++++
4 files changed, 56 insertions(+), 24 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index 4572a9b..353b895 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -73,30 +73,6 @@
#define read_sysreg_el1(r) read_sysreg_elx(r, _EL1, _EL12)
#define write_sysreg_el1(v,r) write_sysreg_elx(v, r, _EL1, _EL12)

-/* The VHE specific system registers and their encoding */
-#define sctlr_EL12 sys_reg(3, 5, 1, 0, 0)
-#define cpacr_EL12 sys_reg(3, 5, 1, 0, 2)
-#define ttbr0_EL12 sys_reg(3, 5, 2, 0, 0)
-#define ttbr1_EL12 sys_reg(3, 5, 2, 0, 1)
-#define tcr_EL12 sys_reg(3, 5, 2, 0, 2)
-#define afsr0_EL12 sys_reg(3, 5, 5, 1, 0)
-#define afsr1_EL12 sys_reg(3, 5, 5, 1, 1)
-#define esr_EL12 sys_reg(3, 5, 5, 2, 0)
-#define far_EL12 sys_reg(3, 5, 6, 0, 0)
-#define mair_EL12 sys_reg(3, 5, 10, 2, 0)
-#define amair_EL12 sys_reg(3, 5, 10, 3, 0)
-#define vbar_EL12 sys_reg(3, 5, 12, 0, 0)
-#define contextidr_EL12 sys_reg(3, 5, 13, 0, 1)
-#define cntkctl_EL12 sys_reg(3, 5, 14, 1, 0)
-#define cntp_tval_EL02 sys_reg(3, 5, 14, 2, 0)
-#define cntp_ctl_EL02 sys_reg(3, 5, 14, 2, 1)
-#define cntp_cval_EL02 sys_reg(3, 5, 14, 2, 2)
-#define cntv_tval_EL02 sys_reg(3, 5, 14, 3, 0)
-#define cntv_ctl_EL02 sys_reg(3, 5, 14, 3, 1)
-#define cntv_cval_EL02 sys_reg(3, 5, 14, 3, 2)
-#define spsr_EL12 sys_reg(3, 5, 4, 0, 0)
-#define elr_EL12 sys_reg(3, 5, 4, 0, 1)
-
/**
* hyp_alternate_select - Generates patchable code sequences that are
* used to switch between two implementations of a function, depending
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index b01c608..b8d4d0c 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -338,6 +338,30 @@
#define SYS_CNTVOFF_EL2 sys_reg(3, 4, 14, 0, 3)
#define SYS_CNTHCTL_EL2 sys_reg(3, 4, 14, 1, 0)

+/* The VHE specific system registers and their encoding */
+#define sctlr_EL12 sys_reg(3, 5, 1, 0, 0)
+#define cpacr_EL12 sys_reg(3, 5, 1, 0, 2)
+#define ttbr0_EL12 sys_reg(3, 5, 2, 0, 0)
+#define ttbr1_EL12 sys_reg(3, 5, 2, 0, 1)
+#define tcr_EL12 sys_reg(3, 5, 2, 0, 2)
+#define afsr0_EL12 sys_reg(3, 5, 5, 1, 0)
+#define afsr1_EL12 sys_reg(3, 5, 5, 1, 1)
+#define esr_EL12 sys_reg(3, 5, 5, 2, 0)
+#define far_EL12 sys_reg(3, 5, 6, 0, 0)
+#define mair_EL12 sys_reg(3, 5, 10, 2, 0)
+#define amair_EL12 sys_reg(3, 5, 10, 3, 0)
+#define vbar_EL12 sys_reg(3, 5, 12, 0, 0)
+#define contextidr_EL12 sys_reg(3, 5, 13, 0, 1)
+#define cntkctl_EL12 sys_reg(3, 5, 14, 1, 0)
+#define cntp_tval_EL02 sys_reg(3, 5, 14, 2, 0)
+#define cntp_ctl_EL02 sys_reg(3, 5, 14, 2, 1)
+#define cntp_cval_EL02 sys_reg(3, 5, 14, 2, 2)
+#define cntv_tval_EL02 sys_reg(3, 5, 14, 3, 0)
+#define cntv_ctl_EL02 sys_reg(3, 5, 14, 3, 1)
+#define cntv_cval_EL02 sys_reg(3, 5, 14, 3, 2)
+#define spsr_EL12 sys_reg(3, 5, 4, 0, 0)
+#define elr_EL12 sys_reg(3, 5, 4, 0, 1)
+
#define SYS_SP_EL2 sys_reg(3, 6, 4, 1, 0)

/* Common SCTLR_ELx flags. */
diff --git a/arch/arm64/kvm/context.c b/arch/arm64/kvm/context.c
index e1bc753..f3d3398 100644
--- a/arch/arm64/kvm/context.c
+++ b/arch/arm64/kvm/context.c
@@ -121,6 +121,13 @@ static void copy_shadow_non_trap_el1_state(struct kvm_vcpu *vcpu, bool setup)
for (i = 0; i < ARRAY_SIZE(el1_non_trap_regs); i++) {
const int sr = el1_non_trap_regs[i];

+ /*
+ * We trap on cntkctl_el12 accesses from virtual EL2 as suppose
+ * to not trapping on cntlctl_el1 accesses.
+ */
+ if (vcpu_el2_e2h_is_set(vcpu) && sr == CNTKCTL_EL1)
+ continue;
+
if (setup)
s_sys_regs[sr] = vcpu_sys_reg(vcpu, sr);
else
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index b3e0cb8..2aa922c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -905,6 +905,14 @@ static inline void access_rw(struct sys_reg_params *p, u64 *sysreg)
*sysreg = p->regval;
}

+static bool access_cntkctl_el12(struct kvm_vcpu *vcpu,
+ struct sys_reg_params *p,
+ const struct sys_reg_desc *r)
+{
+ access_rw(p, &vcpu_sys_reg(vcpu, r->reg));
+ return true;
+}
+
static u64 *get_special_reg(struct kvm_vcpu *vcpu, struct sys_reg_params *p)
{
u64 reg = sys_reg(p->Op0, p->Op1, p->CRn, p->CRm, p->Op2);
@@ -1201,6 +1209,23 @@ static bool access_cpacr(struct kvm_vcpu *vcpu,
{ SYS_DESC(SYS_CNTVOFF_EL2), trap_el2_regs, reset_val, CNTVOFF_EL2, 0 },
{ SYS_DESC(SYS_CNTHCTL_EL2), trap_el2_regs, reset_val, CNTHCTL_EL2, 0 },

+ { SYS_DESC(sctlr_EL12), access_vm_reg, reset_val, SCTLR_EL1, 0x00C50078 },
+ { SYS_DESC(cpacr_EL12), access_cpacr, reset_val, CPACR_EL1, 0 },
+ { SYS_DESC(ttbr0_EL12), access_vm_reg, reset_unknown, TTBR0_EL1 },
+ { SYS_DESC(ttbr1_EL12), access_vm_reg, reset_unknown, TTBR1_EL1 },
+ { SYS_DESC(tcr_EL12), access_vm_reg, reset_val, TCR_EL1, 0 },
+ { SYS_DESC(spsr_EL12), access_spsr},
+ { SYS_DESC(elr_EL12), access_elr},
+ { SYS_DESC(afsr0_EL12), access_vm_reg, reset_unknown, AFSR0_EL1 },
+ { SYS_DESC(afsr1_EL12), access_vm_reg, reset_unknown, AFSR1_EL1 },
+ { SYS_DESC(esr_EL12), access_vm_reg, reset_unknown, ESR_EL1 },
+ { SYS_DESC(far_EL12), access_vm_reg, reset_unknown, FAR_EL1 },
+ { SYS_DESC(mair_EL12), access_vm_reg, reset_unknown, MAIR_EL1 },
+ { SYS_DESC(amair_EL12), access_vm_reg, reset_amair_el1, AMAIR_EL1 },
+ { SYS_DESC(vbar_EL12), access_vbar, reset_val, VBAR_EL1, 0 },
+ { SYS_DESC(contextidr_EL12), access_vm_reg, reset_val, CONTEXTIDR_EL1, 0 },
+ { SYS_DESC(cntkctl_EL12), access_cntkctl_el12, reset_val, CNTKCTL_EL1, 0 },
+
{ SYS_DESC(SYS_SP_EL2), NULL, reset_special, SP_EL2, 0},
};

--
1.9.1