[PATCH 3/9] arm64: KVM: add trap handlers for AArch64 debug registers
Anup Patel
anup.patel at linaro.org
Mon May 19 01:27:46 PDT 2014
On 7 May 2014 20:50, Marc Zyngier <marc.zyngier at arm.com> wrote:
> Add handlers for all the AArch64 debug registers that are accessible
> from EL0 or EL1. The trapping code keeps track of the state of the
> debug registers, allowing for the switch code to implement a lazy
> switching strategy.
>
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
> ---
> arch/arm64/include/asm/kvm_asm.h | 28 ++++++--
> arch/arm64/include/asm/kvm_host.h | 3 +
> arch/arm64/kvm/sys_regs.c | 130 +++++++++++++++++++++++++++++++++++++-
> 3 files changed, 151 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index 9fcd54b..e6b159a 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -43,14 +43,25 @@
> #define AMAIR_EL1 19 /* Aux Memory Attribute Indirection Register */
> #define CNTKCTL_EL1 20 /* Timer Control Register (EL1) */
> #define PAR_EL1 21 /* Physical Address Register */
> +#define MDSCR_EL1 22 /* Monitor Debug System Control Register */
> +#define DBGBCR0_EL1 23 /* Debug Breakpoint Control Registers (0-15) */
> +#define DBGBCR15_EL1 38
> +#define DBGBVR0_EL1 39 /* Debug Breakpoint Value Registers (0-15) */
> +#define DBGBVR15_EL1 54
> +#define DBGWCR0_EL1 55 /* Debug Watchpoint Control Registers (0-15) */
> +#define DBGWCR15_EL1 70
> +#define DBGWVR0_EL1 71 /* Debug Watchpoint Value Registers (0-15) */
> +#define DBGWVR15_EL1 86
> +#define MDCCINT_EL1 87 /* Monitor Debug Comms Channel Interrupt Enable Reg */
> +
> /* 32bit specific registers. Keep them at the end of the range */
> -#define DACR32_EL2 22 /* Domain Access Control Register */
> -#define IFSR32_EL2 23 /* Instruction Fault Status Register */
> -#define FPEXC32_EL2 24 /* Floating-Point Exception Control Register */
> -#define DBGVCR32_EL2 25 /* Debug Vector Catch Register */
> -#define TEECR32_EL1 26 /* ThumbEE Configuration Register */
> -#define TEEHBR32_EL1 27 /* ThumbEE Handler Base Register */
> -#define NR_SYS_REGS 28
> +#define DACR32_EL2 88 /* Domain Access Control Register */
> +#define IFSR32_EL2 89 /* Instruction Fault Status Register */
> +#define FPEXC32_EL2 90 /* Floating-Point Exception Control Register */
> +#define DBGVCR32_EL2 91 /* Debug Vector Catch Register */
> +#define TEECR32_EL1 92 /* ThumbEE Configuration Register */
> +#define TEEHBR32_EL1 93 /* ThumbEE Handler Base Register */
> +#define NR_SYS_REGS 94
>
> /* 32bit mapping */
> #define c0_MPIDR (MPIDR_EL1 * 2) /* MultiProcessor ID Register */
> @@ -87,6 +98,9 @@
> #define ARM_EXCEPTION_IRQ 0
> #define ARM_EXCEPTION_TRAP 1
>
> +#define KVM_ARM64_DEBUG_DIRTY_SHIFT 0
> +#define KVM_ARM64_DEBUG_DIRTY (1 << KVM_ARM64_DEBUG_DIRTY_SHIFT)
> +
> #ifndef __ASSEMBLY__
> struct kvm;
> struct kvm_vcpu;
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 0a1d697..4737961 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -101,6 +101,9 @@ struct kvm_vcpu_arch {
> /* Exception Information */
> struct kvm_vcpu_fault_info fault;
>
> + /* Debug state */
> + u64 debug_flags;
> +
> /* Pointer to host CPU context */
> kvm_cpu_context_t *host_cpu_context;
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index fc8d4e3..618d4fb 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -30,6 +30,7 @@
> #include <asm/kvm_mmu.h>
> #include <asm/cacheflush.h>
> #include <asm/cputype.h>
> +#include <asm/debug-monitors.h>
> #include <trace/events/kvm.h>
>
> #include "sys_regs.h"
> @@ -173,6 +174,58 @@ static bool trap_wi_raz(struct kvm_vcpu *vcpu,
> return read_zero(vcpu, p);
> }
>
> +static bool trap_oslsr_el1(struct kvm_vcpu *vcpu,
> + const struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + if (p->is_write) {
> + return ignore_write(vcpu, p);
> + } else {
> + *vcpu_reg(vcpu, p->Rt) = (1 << 3);
> + return true;
> + }
> +}
> +
> +static bool trap_dbgauthstatus_el1(struct kvm_vcpu *vcpu,
> + const struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + if (p->is_write) {
> + return ignore_write(vcpu, p);
> + } else {
> + *vcpu_reg(vcpu, p->Rt) = 0x2222; /* Implemented and disabled */
> + return true;
> + }
> +}
> +
> +/*
> + * Trap handler for DBG[BW][CV]Rn_EL1 and MDSCR_EL1. We track the
> + * "dirtiness" of the registers.
> + */
> +static bool trap_debug_regs(struct kvm_vcpu *vcpu,
> + const struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + /*
> + * The best thing to do would be to trap MDSCR_EL1
> + * independently, test if DBG_MDSCR_KDE or DBG_MDSCR_MDE is
> + * getting set, and only set the DIRTY bit in that case.
> + *
> + * Unfortunately, "old" Linux kernels tend to hit MDSCR_EL1
> + * like a woodpecker on a tree, and it is better to disable
> + * trapping as soon as possible in this case. Some day, make
> + * this a tuneable...
> + */
> + if (p->is_write) {
> + vcpu_sys_reg(vcpu, r->reg) = *vcpu_reg(vcpu, p->Rt);
> + vcpu->arch.debug_flags |= KVM_ARM64_DEBUG_DIRTY;
> + } else {
> + *vcpu_reg(vcpu, p->Rt) = vcpu_sys_reg(vcpu, r->reg);
> + }
> +
> + return true;
> +}
> +
> static void reset_amair_el1(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
> {
> u64 amair;
> @@ -189,6 +242,21 @@ static void reset_mpidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
> vcpu_sys_reg(vcpu, MPIDR_EL1) = (1UL << 31) | (vcpu->vcpu_id & 0xff);
> }
>
> +/* Silly macro to expand the DBG{BCR,BVR,WVR,WCR}n_EL1 registers in one go*/
> +#define DBG_BCR_BVR_WCR_WVR_EL1(n) \
> + /* DBGBVRn_EL1 */ \
> + { Op0(0b10), Op1(0b000), CRn(0b0000), CRm((n)), Op2(0b100), \
> + trap_debug_regs, reset_val, (DBGBCR0_EL1 + (n)), 0 }, \
> + /* DBGBCRn_EL1 */ \
> + { Op0(0b10), Op1(0b000), CRn(0b0000), CRm((n)), Op2(0b101), \
> + trap_debug_regs, reset_val, (DBGBVR0_EL1 + (n)), 0 }, \
> + /* DBGWVRn_EL1 */ \
> + { Op0(0b10), Op1(0b000), CRn(0b0000), CRm((n)), Op2(0b110), \
> + trap_debug_regs, reset_val, (DBGWCR0_EL1 + (n)), 0 }, \
> + /* DBGWCRn_EL1 */ \
> + { Op0(0b10), Op1(0b000), CRn(0b0000), CRm((n)), Op2(0b111), \
> + trap_debug_regs, reset_val, (DBGWVR0_EL1 + (n)), 0 }
> +
> /*
> * Architected system registers.
> * Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2
> @@ -200,9 +268,6 @@ static void reset_mpidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
> * Therefore we tell the guest we have 0 counters. Unfortunately, we
> * must always support PMCCNTR (the cycle counter): we just RAZ/WI for
> * all PM registers, which doesn't crash the guest kernel at least.
> - *
> - * Same goes for the whole debug infrastructure, which probably breaks
> - * some guest functionnality. This should be fixed.
> */
> static const struct sys_reg_desc sys_reg_descs[] = {
> /* DC ISW */
> @@ -215,12 +280,71 @@ static const struct sys_reg_desc sys_reg_descs[] = {
> { Op0(0b01), Op1(0b000), CRn(0b0111), CRm(0b1110), Op2(0b010),
> access_dcsw },
>
> + DBG_BCR_BVR_WCR_WVR_EL1(0),
> + DBG_BCR_BVR_WCR_WVR_EL1(1),
> + /* MDCCINT_EL1 */
> + { Op0(0b10), Op1(0b000), CRn(0b0000), CRm(0b0010), Op2(0b000),
> + trap_debug_regs, reset_val, MDCCINT_EL1, 0 },
> + /* MDSCR_EL1 */
> + { Op0(0b10), Op1(0b000), CRn(0b0000), CRm(0b0010), Op2(0b010),
> + trap_debug_regs, reset_val, MDSCR_EL1, 0 },
> + DBG_BCR_BVR_WCR_WVR_EL1(2),
> + DBG_BCR_BVR_WCR_WVR_EL1(3),
> + DBG_BCR_BVR_WCR_WVR_EL1(4),
> + DBG_BCR_BVR_WCR_WVR_EL1(5),
> + DBG_BCR_BVR_WCR_WVR_EL1(6),
> + DBG_BCR_BVR_WCR_WVR_EL1(7),
> + DBG_BCR_BVR_WCR_WVR_EL1(8),
> + DBG_BCR_BVR_WCR_WVR_EL1(9),
> + DBG_BCR_BVR_WCR_WVR_EL1(10),
> + DBG_BCR_BVR_WCR_WVR_EL1(11),
> + DBG_BCR_BVR_WCR_WVR_EL1(12),
> + DBG_BCR_BVR_WCR_WVR_EL1(13),
> + DBG_BCR_BVR_WCR_WVR_EL1(14),
> + DBG_BCR_BVR_WCR_WVR_EL1(15),
> +
> + /* MDRAR_EL1 */
> + { Op0(0b10), Op1(0b000), CRn(0b0001), CRm(0b0000), Op2(0b000),
> + trap_wi_raz },
> + /* OSLAR_EL1 */
> + { Op0(0b10), Op1(0b000), CRn(0b0001), CRm(0b0000), Op2(0b100),
> + trap_wi_raz },
> + /* OSLSR_EL1 */
> + { Op0(0b10), Op1(0b000), CRn(0b0001), CRm(0b0001), Op2(0b100),
> + trap_oslsr_el1 },
> + /* OSDLR_EL1 */
> + { Op0(0b10), Op1(0b000), CRn(0b0001), CRm(0b0011), Op2(0b100),
> + trap_wi_raz },
> + /* DBGPRCR_EL1 */
> + { Op0(0b10), Op1(0b000), CRn(0b0001), CRm(0b0100), Op2(0b100),
> + trap_wi_raz },
> + /* DBGCLAIMSET_EL1 */
> + { Op0(0b10), Op1(0b000), CRn(0b0111), CRm(0b1000), Op2(0b110),
> + trap_wi_raz },
> + /* DBGCLAIMCLR_EL1 */
> + { Op0(0b10), Op1(0b000), CRn(0b0111), CRm(0b1001), Op2(0b110),
> + trap_wi_raz },
> + /* DBGAUTHSTATUS_EL1 */
> + { Op0(0b10), Op1(0b000), CRn(0b0111), CRm(0b1110), Op2(0b110),
> + trap_dbgauthstatus_el1 },
> +
> /* TEECR32_EL1 */
> { Op0(0b10), Op1(0b010), CRn(0b0000), CRm(0b0000), Op2(0b000),
> NULL, reset_val, TEECR32_EL1, 0 },
> /* TEEHBR32_EL1 */
> { Op0(0b10), Op1(0b010), CRn(0b0001), CRm(0b0000), Op2(0b000),
> NULL, reset_val, TEEHBR32_EL1, 0 },
> +
> + /* MDCCSR_EL1 */
> + { Op0(0b10), Op1(0b011), CRn(0b0000), CRm(0b0001), Op2(0b000),
> + trap_wi_raz },
> + /* DBGDTR_EL0 */
> + { Op0(0b10), Op1(0b011), CRn(0b0000), CRm(0b0100), Op2(0b000),
> + trap_wi_raz },
> + /* DBGDTR[TR]X_EL0 */
> + { Op0(0b10), Op1(0b011), CRn(0b0000), CRm(0b0101), Op2(0b000),
> + trap_wi_raz },
> +
> /* DBGVCR32_EL2 */
> { Op0(0b10), Op1(0b100), CRn(0b0000), CRm(0b0111), Op2(0b000),
> NULL, reset_val, DBGVCR32_EL2, 0 },
> --
> 1.8.3.4
>
> _______________________________________________
> kvmarm mailing list
> kvmarm at lists.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
Looks good to me.
FWIW, Reviewed-by: Anup Patel <anup.patel at linaro.org>
--
Anup
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