On 11/09/15 09:54, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>
> Add reset handler which gets host value of PMCR_EL0 and make writable
> bits architecturally UNKNOWN. Add a common access handler for PMU
> registers which emulates writing and reading register and add emulation
> for PMCR.
>
> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> ---
> arch/arm64/kvm/sys_regs.c | 76 +++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 74 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index c370b40..db1be44 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -33,6 +33,7 @@
> #include <asm/kvm_emulate.h>
> #include <asm/kvm_host.h>
> #include <asm/kvm_mmu.h>
> +#include <asm/pmu.h>
>
> #include <trace/events/kvm.h>
>
> @@ -236,6 +237,48 @@ static void reset_mpidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
> vcpu_sys_reg(vcpu, MPIDR_EL1) = (1ULL << 31) | mpidr;
> }
>
> +static void reset_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
> +{
> + u32 pmcr;
> +
> + asm volatile("mrs %0, pmcr_el0\n" : "=r" (pmcr));
> + /* Writable bits of PMCR_EL0 (ARMV8_PMCR_MASK) is reset to UNKNOWN*/
> + if (!vcpu_mode_is_32bit(vcpu))
> + vcpu_sys_reg(vcpu, r->reg) = (pmcr & ~ARMV8_PMCR_MASK)
> + | (ARMV8_PMCR_MASK & 0xdecafbad);
> + else
> + vcpu_cp15(vcpu, r->reg) = (pmcr & ~ARMV8_PMCR_MASK)
> + | (ARMV8_PMCR_MASK & 0xdecafbad);
I have some concerns about blindly reusing the top bits of the host's
PMCR_EL0 register, specially when it comes to the PMCR_EL0.N. Given that
we're fully emulating the PMU, shouldn't we simply define how many
counters we're emulating?
> +}
> +
> +/* PMU registers accessor. */
> +static bool access_pmu_regs(struct kvm_vcpu *vcpu,
> + const struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + unsigned long val;
> +
> + if (p->is_write) {
> + switch (r->reg) {
> + case PMCR_EL0: {
> + /* Only update writeable bits of PMCR */
> + val = vcpu_sys_reg(vcpu, r->reg);
> + val &= ~ARMV8_PMCR_MASK;
> + val |= *vcpu_reg(vcpu, p->Rt) & ARMV8_PMCR_MASK;
> + vcpu_sys_reg(vcpu, r->reg) = val;
> + break;
> + }
> + default:
> + vcpu_sys_reg(vcpu, r->reg) = *vcpu_reg(vcpu, p->Rt);
> + break;
> + }
> + } else {
> + *vcpu_reg(vcpu, p->Rt) = vcpu_sys_reg(vcpu, r->reg);
> + }
> +
> + return true;
> +}
> +
> /* 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 */ \
> @@ -427,7 +470,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>
> /* PMCR_EL0 */
> { Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b000),
> - trap_raz_wi },
> + access_pmu_regs, reset_pmcr, PMCR_EL0, },
> /* PMCNTENSET_EL0 */
> { Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b001),
> trap_raz_wi },
> @@ -632,6 +675,34 @@ static const struct sys_reg_desc cp14_64_regs[] = {
> { Op1( 0), CRm( 2), .access = trap_raz_wi },
> };
>
> +/* PMU CP15 registers accessor. */
> +static bool access_pmu_cp15_regs(struct kvm_vcpu *vcpu,
> + const struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + unsigned long val;
> +
> + if (p->is_write) {
> + switch (r->reg) {
> + case c9_PMCR: {
> + /* Only update writeable bits of PMCR */
> + val = vcpu_cp15(vcpu, r->reg);
> + val &= ~ARMV8_PMCR_MASK;
> + val |= *vcpu_reg(vcpu, p->Rt) & ARMV8_PMCR_MASK;
> + vcpu_cp15(vcpu, r->reg) = val;
> + break;
> + }
> + default:
> + vcpu_cp15(vcpu, r->reg) = *vcpu_reg(vcpu, p->Rt);
> + break;
> + }
> + } else {
> + *vcpu_reg(vcpu, p->Rt) = vcpu_cp15(vcpu, r->reg);
> + }
> +
> + return true;
> +}
> +
> /*
> * Trapped cp15 registers. TTBR0/TTBR1 get a double encoding,
> * depending on the way they are accessed (as a 32bit or a 64bit
> @@ -660,7 +731,8 @@ static const struct sys_reg_desc cp15_regs[] = {
> { Op1( 0), CRn( 7), CRm(14), Op2( 2), access_dcsw },
>
> /* PMU */
> - { Op1( 0), CRn( 9), CRm(12), Op2( 0), trap_raz_wi },
> + { Op1( 0), CRn( 9), CRm(12), Op2( 0), access_pmu_cp15_regs,
> + reset_pmcr, c9_PMCR },
> { Op1( 0), CRn( 9), CRm(12), Op2( 1), trap_raz_wi },
> { Op1( 0), CRn( 9), CRm(12), Op2( 2), trap_raz_wi },
> { Op1( 0), CRn( 9), CRm(12), Op2( 3), trap_raz_wi },
>
--
Jazz is not dead. It just smells funny...
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