On Thu, Jan 28, 2016 at 04:36:35PM +0100, Andrew Jones wrote:
> On Wed, Jan 27, 2016 at 11:51:32AM +0800, 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 except PMCR.E which is zero. Add an access
> > handler for PMCR.
> >
> > Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> > ---
> > arch/arm64/kvm/sys_regs.c | 42 ++++++++++++++++++++++++++++++++++++++++--
> > include/kvm/arm_pmu.h | 4 ++++
> > 2 files changed, 44 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> > index eec3598..97fea84 100644
> > --- a/arch/arm64/kvm/sys_regs.c
> > +++ b/arch/arm64/kvm/sys_regs.c
> > @@ -34,6 +34,7 @@
> > #include <asm/kvm_emulate.h>
> > #include <asm/kvm_host.h>
> > #include <asm/kvm_mmu.h>
> > +#include <asm/pmu.h>
> >
> > #include <trace/events/kvm.h>
> >
> > @@ -439,6 +440,43 @@ 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)
> > +{
> > + u64 pmcr, val;
> > +
> > + asm volatile("mrs %0, pmcr_el0\n" : "=r" (pmcr));
> > + /* Writable bits of PMCR_EL0 (ARMV8_PMCR_MASK) is reset to UNKNOWN
> > + * except PMCR.E resetting to zero.
> > + */
> > + val = ((pmcr & ~ARMV8_PMCR_MASK) | (ARMV8_PMCR_MASK & 0xdecafbad))
> > + & (~ARMV8_PMCR_E);
> > + vcpu_sys_reg(vcpu, PMCR_EL0) = val;
> > +}
> > +
> > +static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
> > + const struct sys_reg_desc *r)
> > +{
> > + u64 val;
> > +
> > + if (!kvm_arm_pmu_v3_ready(vcpu))
> > + return trap_raz_wi(vcpu, p, r);
> > +
> > + if (p->is_write) {
> > + /* Only update writeable bits of PMCR */
> > + val = vcpu_sys_reg(vcpu, PMCR_EL0);
> > + val &= ~ARMV8_PMCR_MASK;
> > + val |= p->regval & ARMV8_PMCR_MASK;
> > + vcpu_sys_reg(vcpu, PMCR_EL0) = val;
> > + } else {
> > + /* PMCR.P & PMCR.C are RAZ */
> > + val = vcpu_sys_reg(vcpu, PMCR_EL0)
> > + & ~(ARMV8_PMCR_P | ARMV8_PMCR_C);
> > + p->regval = val;
>
> Should we also be setting the IMP, IDCODE, and N fields here to the
> values of the host PE?
Not sure how I skimmed over the reset_pmcr doing this when I first
read it. I'm now wondering if we want to always expose the host's
IMP, IDCODE, N though (migration concerns). Although we have a ton
of invariant sys regs already... So I guess this is a bridge to burn
another day.
>
> > + }
> > +
> > + 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 */ \
> > @@ -623,7 +661,7 @@ 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_pmcr, reset_pmcr, },
> > /* PMCNTENSET_EL0 */
> > { Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b001),
> > trap_raz_wi },
> > @@ -885,7 +923,7 @@ 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_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 },
> > diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
> > index be220ee..32fee2d 100644
> > --- a/include/kvm/arm_pmu.h
> > +++ b/include/kvm/arm_pmu.h
> > @@ -34,9 +34,13 @@ struct kvm_pmu {
> > struct kvm_pmc pmc[ARMV8_MAX_COUNTERS];
> > bool ready;
> > };
> > +
> > +#define kvm_arm_pmu_v3_ready(v) ((v)->arch.pmu.ready)
> > #else
> > struct kvm_pmu {
> > };
> > +
> > +#define kvm_arm_pmu_v3_ready(v) (false)
> > #endif
> >
> > #endif
> > --
> > 2.0.4
> >
> >
> > --
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