| Message ID | 20121110154328.2836.78376.stgit@chazy-air (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, Nov 10, 2012 at 03:43:28PM +0000, Christoffer Dall wrote: > The Cache Size Selection Register (CSSELR) selects the current Cache > Size ID Register (CCSIDR). You write which cache you are interested > in to CSSELR, and read the information out of CCSIDR. > > Which cache numbers are valid is known by reading the Cache Level ID > Register (CLIDR). > > To export this state to userspace, we add a KVM_REG_ARM_DEMUX > numberspace (17), which uses 8 bits to represent which register is > being demultiplexed (0 for CCSIDR), and the lower 8 bits to represent > this demultiplexing (in our case, the CSSELR value, which is 4 bits). > > Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> > Signed-off-by: Rusty Russell <rusty.russell@linaro.org> [...] > Documentation/virtual/kvm/api.txt | 2 > arch/arm/include/uapi/asm/kvm.h | 9 ++ > arch/arm/kvm/coproc.c | 163 ++++++++++++++++++++++++++++++++++++- > 3 files changed, 171 insertions(+), 3 deletions(-) > > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt > index 9671cd2..bf8f99c 100644 > --- a/Documentation/virtual/kvm/api.txt > +++ b/Documentation/virtual/kvm/api.txt > @@ -1804,6 +1804,8 @@ ARM 32-bit CP15 registers have the following id bit patterns: > ARM 64-bit CP15 registers have the following id bit patterns: > 0x4003 0000 000F <zero:1> <zero:4> <crm:4> <opc1:4> <zero:3> > > +ARM CCSIDR registers are demultiplexed by CSSELR value: > + 0x4002 0000 0011 00 <csselr:8> > > 4.69 KVM_GET_ONE_REG > > diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h > index a807d9a..78a629c 100644 > --- a/arch/arm/include/uapi/asm/kvm.h > +++ b/arch/arm/include/uapi/asm/kvm.h > @@ -80,6 +80,15 @@ struct kvm_arch_memory_slot { > #define KVM_REG_ARM_CORE (0x0010 << KVM_REG_ARM_COPROC_SHIFT) > #define KVM_REG_ARM_CORE_REG(name) (offsetof(struct kvm_regs, name) / 4) > > +/* Some registers need more space to represent values. */ > +#define KVM_REG_ARM_DEMUX (0x0011 << KVM_REG_ARM_COPROC_SHIFT) > +#define KVM_REG_ARM_DEMUX_ID_MASK 0x000000000000FF00 > +#define KVM_REG_ARM_DEMUX_ID_SHIFT 8 > +#define KVM_REG_ARM_DEMUX_ID_CCSIDR (0x00 << KVM_REG_ARM_DEMUX_ID_SHIFT) > +#define KVM_REG_ARM_DEMUX_VAL_MASK 0x00000000000000FF > +#define KVM_REG_ARM_DEMUX_VAL_SHIFT 0 > + > + > /* KVM_IRQ_LINE irq field index values */ > #define KVM_ARM_IRQ_TYPE_SHIFT 24 > #define KVM_ARM_IRQ_TYPE_MASK 0xff > diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c > index 95a0f5e..9ce5861 100644 > --- a/arch/arm/kvm/coproc.c > +++ b/arch/arm/kvm/coproc.c > @@ -35,6 +35,12 @@ > * Co-processor emulation > *****************************************************************************/ > > +/* 3 bits per cache level, as per CLIDR, but non-existent caches always 0 */ > +static u32 cache_levels; > + > +/* CSSELR values; used to index KVM_REG_ARM_DEMUX_ID_CCSIDR */ > +#define CSSELR_MAX 12 > + > int kvm_handle_cp10_id(struct kvm_vcpu *vcpu, struct kvm_run *run) > { > kvm_inject_undefined(vcpu); > @@ -548,11 +554,112 @@ static int set_invariant_cp15(u64 id, void __user *uaddr) > return 0; > } > > +static bool is_valid_cache(u32 val) > +{ > + u32 level, ctype; > + > + if (val >= CSSELR_MAX) > + return -ENOENT; > + > + /* Bottom bit is Instruction or Data bit. Next 3 bits are level. */ > + level = (val >> 1); > + ctype = (cache_levels >> (level * 3)) & 7; > + > + switch (ctype) { > + case 0: /* No cache */ > + return false; > + case 1: /* Instruction cache only */ > + return (val & 1); > + case 2: /* Data cache only */ > + case 4: /* Unified cache */ > + return !(val & 1); > + case 3: /* Separate instruction and data caches */ > + return true; > + default: /* Reserved: we can't know instruction or data. */ > + return false; > + } > +} > + > +/* Which cache CCSIDR represents depends on CSSELR value. */ > +static u32 get_ccsidr(u32 csselr) > +{ > + u32 ccsidr; > + > + /* Make sure noone else changes CSSELR during this! */ > + local_irq_disable(); > + /* Put value into CSSELR */ > + asm volatile("mcr p15, 2, %0, c0, c0, 0" : : "r" (csselr)); You need an isb() here, otherwise you might still address the wrong cache (the two accesses don't hazard in the CPU). Will
On Mon, Nov 19, 2012 at 10:03 AM, Will Deacon <will.deacon@arm.com> wrote: > On Sat, Nov 10, 2012 at 03:43:28PM +0000, Christoffer Dall wrote: >> The Cache Size Selection Register (CSSELR) selects the current Cache >> Size ID Register (CCSIDR). You write which cache you are interested >> in to CSSELR, and read the information out of CCSIDR. >> >> Which cache numbers are valid is known by reading the Cache Level ID >> Register (CLIDR). >> >> To export this state to userspace, we add a KVM_REG_ARM_DEMUX >> numberspace (17), which uses 8 bits to represent which register is >> being demultiplexed (0 for CCSIDR), and the lower 8 bits to represent >> this demultiplexing (in our case, the CSSELR value, which is 4 bits). >> >> Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> >> Signed-off-by: Rusty Russell <rusty.russell@linaro.org> > > [...] > >> Documentation/virtual/kvm/api.txt | 2 >> arch/arm/include/uapi/asm/kvm.h | 9 ++ >> arch/arm/kvm/coproc.c | 163 ++++++++++++++++++++++++++++++++++++- >> 3 files changed, 171 insertions(+), 3 deletions(-) >> >> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt >> index 9671cd2..bf8f99c 100644 >> --- a/Documentation/virtual/kvm/api.txt >> +++ b/Documentation/virtual/kvm/api.txt >> @@ -1804,6 +1804,8 @@ ARM 32-bit CP15 registers have the following id bit patterns: >> ARM 64-bit CP15 registers have the following id bit patterns: >> 0x4003 0000 000F <zero:1> <zero:4> <crm:4> <opc1:4> <zero:3> >> >> +ARM CCSIDR registers are demultiplexed by CSSELR value: >> + 0x4002 0000 0011 00 <csselr:8> >> >> 4.69 KVM_GET_ONE_REG >> >> diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h >> index a807d9a..78a629c 100644 >> --- a/arch/arm/include/uapi/asm/kvm.h >> +++ b/arch/arm/include/uapi/asm/kvm.h >> @@ -80,6 +80,15 @@ struct kvm_arch_memory_slot { >> #define KVM_REG_ARM_CORE (0x0010 << KVM_REG_ARM_COPROC_SHIFT) >> #define KVM_REG_ARM_CORE_REG(name) (offsetof(struct kvm_regs, name) / 4) >> >> +/* Some registers need more space to represent values. */ >> +#define KVM_REG_ARM_DEMUX (0x0011 << KVM_REG_ARM_COPROC_SHIFT) >> +#define KVM_REG_ARM_DEMUX_ID_MASK 0x000000000000FF00 >> +#define KVM_REG_ARM_DEMUX_ID_SHIFT 8 >> +#define KVM_REG_ARM_DEMUX_ID_CCSIDR (0x00 << KVM_REG_ARM_DEMUX_ID_SHIFT) >> +#define KVM_REG_ARM_DEMUX_VAL_MASK 0x00000000000000FF >> +#define KVM_REG_ARM_DEMUX_VAL_SHIFT 0 >> + >> + >> /* KVM_IRQ_LINE irq field index values */ >> #define KVM_ARM_IRQ_TYPE_SHIFT 24 >> #define KVM_ARM_IRQ_TYPE_MASK 0xff >> diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c >> index 95a0f5e..9ce5861 100644 >> --- a/arch/arm/kvm/coproc.c >> +++ b/arch/arm/kvm/coproc.c >> @@ -35,6 +35,12 @@ >> * Co-processor emulation >> *****************************************************************************/ >> >> +/* 3 bits per cache level, as per CLIDR, but non-existent caches always 0 */ >> +static u32 cache_levels; >> + >> +/* CSSELR values; used to index KVM_REG_ARM_DEMUX_ID_CCSIDR */ >> +#define CSSELR_MAX 12 >> + >> int kvm_handle_cp10_id(struct kvm_vcpu *vcpu, struct kvm_run *run) >> { >> kvm_inject_undefined(vcpu); >> @@ -548,11 +554,112 @@ static int set_invariant_cp15(u64 id, void __user *uaddr) >> return 0; >> } >> >> +static bool is_valid_cache(u32 val) >> +{ >> + u32 level, ctype; >> + >> + if (val >= CSSELR_MAX) >> + return -ENOENT; >> + >> + /* Bottom bit is Instruction or Data bit. Next 3 bits are level. */ >> + level = (val >> 1); >> + ctype = (cache_levels >> (level * 3)) & 7; >> + >> + switch (ctype) { >> + case 0: /* No cache */ >> + return false; >> + case 1: /* Instruction cache only */ >> + return (val & 1); >> + case 2: /* Data cache only */ >> + case 4: /* Unified cache */ >> + return !(val & 1); >> + case 3: /* Separate instruction and data caches */ >> + return true; >> + default: /* Reserved: we can't know instruction or data. */ >> + return false; >> + } >> +} >> + >> +/* Which cache CCSIDR represents depends on CSSELR value. */ >> +static u32 get_ccsidr(u32 csselr) >> +{ >> + u32 ccsidr; >> + >> + /* Make sure noone else changes CSSELR during this! */ >> + local_irq_disable(); >> + /* Put value into CSSELR */ >> + asm volatile("mcr p15, 2, %0, c0, c0, 0" : : "r" (csselr)); > > You need an isb() here, otherwise you might still address the wrong > cache (the two accesses don't hazard in the CPU). > that was just totally obvious ;)
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 9671cd2..bf8f99c 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1804,6 +1804,8 @@ ARM 32-bit CP15 registers have the following id bit patterns: ARM 64-bit CP15 registers have the following id bit patterns: 0x4003 0000 000F <zero:1> <zero:4> <crm:4> <opc1:4> <zero:3> +ARM CCSIDR registers are demultiplexed by CSSELR value: + 0x4002 0000 0011 00 <csselr:8> 4.69 KVM_GET_ONE_REG diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h index a807d9a..78a629c 100644 --- a/arch/arm/include/uapi/asm/kvm.h +++ b/arch/arm/include/uapi/asm/kvm.h @@ -80,6 +80,15 @@ struct kvm_arch_memory_slot { #define KVM_REG_ARM_CORE (0x0010 << KVM_REG_ARM_COPROC_SHIFT) #define KVM_REG_ARM_CORE_REG(name) (offsetof(struct kvm_regs, name) / 4) +/* Some registers need more space to represent values. */ +#define KVM_REG_ARM_DEMUX (0x0011 << KVM_REG_ARM_COPROC_SHIFT) +#define KVM_REG_ARM_DEMUX_ID_MASK 0x000000000000FF00 +#define KVM_REG_ARM_DEMUX_ID_SHIFT 8 +#define KVM_REG_ARM_DEMUX_ID_CCSIDR (0x00 << KVM_REG_ARM_DEMUX_ID_SHIFT) +#define KVM_REG_ARM_DEMUX_VAL_MASK 0x00000000000000FF +#define KVM_REG_ARM_DEMUX_VAL_SHIFT 0 + + /* KVM_IRQ_LINE irq field index values */ #define KVM_ARM_IRQ_TYPE_SHIFT 24 #define KVM_ARM_IRQ_TYPE_MASK 0xff diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c index 95a0f5e..9ce5861 100644 --- a/arch/arm/kvm/coproc.c +++ b/arch/arm/kvm/coproc.c @@ -35,6 +35,12 @@ * Co-processor emulation *****************************************************************************/ +/* 3 bits per cache level, as per CLIDR, but non-existent caches always 0 */ +static u32 cache_levels; + +/* CSSELR values; used to index KVM_REG_ARM_DEMUX_ID_CCSIDR */ +#define CSSELR_MAX 12 + int kvm_handle_cp10_id(struct kvm_vcpu *vcpu, struct kvm_run *run) { kvm_inject_undefined(vcpu); @@ -548,11 +554,112 @@ static int set_invariant_cp15(u64 id, void __user *uaddr) return 0; } +static bool is_valid_cache(u32 val) +{ + u32 level, ctype; + + if (val >= CSSELR_MAX) + return -ENOENT; + + /* Bottom bit is Instruction or Data bit. Next 3 bits are level. */ + level = (val >> 1); + ctype = (cache_levels >> (level * 3)) & 7; + + switch (ctype) { + case 0: /* No cache */ + return false; + case 1: /* Instruction cache only */ + return (val & 1); + case 2: /* Data cache only */ + case 4: /* Unified cache */ + return !(val & 1); + case 3: /* Separate instruction and data caches */ + return true; + default: /* Reserved: we can't know instruction or data. */ + return false; + } +} + +/* Which cache CCSIDR represents depends on CSSELR value. */ +static u32 get_ccsidr(u32 csselr) +{ + u32 ccsidr; + + /* Make sure noone else changes CSSELR during this! */ + local_irq_disable(); + /* Put value into CSSELR */ + asm volatile("mcr p15, 2, %0, c0, c0, 0" : : "r" (csselr)); + /* Read result out of CCSIDR */ + asm volatile("mrc p15, 1, %0, c0, c0, 0" : "=r" (ccsidr)); + local_irq_enable(); + + return ccsidr; +} + +static int demux_c15_get(u64 id, void __user *uaddr) +{ + u32 val; + u32 __user *uval = uaddr; + + /* Fail if we have unknown bits set. */ + if (id & ~(KVM_REG_ARCH_MASK|KVM_REG_SIZE_MASK|KVM_REG_ARM_COPROC_MASK + | ((1 << KVM_REG_ARM_COPROC_SHIFT)-1))) + return -ENOENT; + + switch (id & KVM_REG_ARM_DEMUX_ID_MASK) { + case KVM_REG_ARM_DEMUX_ID_CCSIDR: + if (KVM_REG_SIZE(id) != 4) + return -ENOENT; + val = (id & KVM_REG_ARM_DEMUX_VAL_MASK) + >> KVM_REG_ARM_DEMUX_VAL_SHIFT; + if (!is_valid_cache(val)) + return -ENOENT; + + return put_user(get_ccsidr(val), uval); + default: + return -ENOENT; + } +} + +static int demux_c15_set(u64 id, void __user *uaddr) +{ + u32 val, newval; + u32 __user *uval = uaddr; + + /* Fail if we have unknown bits set. */ + if (id & ~(KVM_REG_ARCH_MASK|KVM_REG_SIZE_MASK|KVM_REG_ARM_COPROC_MASK + | ((1 << KVM_REG_ARM_COPROC_SHIFT)-1))) + return -ENOENT; + + switch (id & KVM_REG_ARM_DEMUX_ID_MASK) { + case KVM_REG_ARM_DEMUX_ID_CCSIDR: + if (KVM_REG_SIZE(id) != 4) + return -ENOENT; + val = (id & KVM_REG_ARM_DEMUX_VAL_MASK) + >> KVM_REG_ARM_DEMUX_VAL_SHIFT; + if (!is_valid_cache(val)) + return -ENOENT; + + if (get_user(newval, uval)) + return -EFAULT; + + /* This is also invariant: you can't change it. */ + if (newval != get_ccsidr(val)) + return -EINVAL; + return 0; + default: + return -ENOENT; + } +} + int kvm_arm_coproc_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) { const struct coproc_reg *r; void __user *uaddr = (void __user *)(long)reg->addr; + if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_DEMUX) + return demux_c15_get(reg->id, uaddr); + r = index_to_coproc_reg(vcpu, reg->id); if (!r) return get_invariant_cp15(reg->id, uaddr); @@ -566,6 +673,9 @@ int kvm_arm_coproc_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) const struct coproc_reg *r; void __user *uaddr = (void __user *)(long)reg->addr; + if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_DEMUX) + return demux_c15_set(reg->id, uaddr); + r = index_to_coproc_reg(vcpu, reg->id); if (!r) return set_invariant_cp15(reg->id, uaddr); @@ -574,6 +684,33 @@ int kvm_arm_coproc_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) return reg_from_user(&vcpu->arch.cp15[r->reg], uaddr, reg->id); } +static unsigned int num_demux_regs(void) +{ + unsigned int i, count = 0; + + for (i = 0; i < CSSELR_MAX; i++) + if (is_valid_cache(i)) + count++; + + return count; +} + +static int write_demux_regids(u64 __user *uindices) +{ + u64 val = KVM_REG_ARM | KVM_REG_SIZE_U32 | KVM_REG_ARM_DEMUX; + unsigned int i; + + val |= KVM_REG_ARM_DEMUX_ID_CCSIDR; + for (i = 0; i < CSSELR_MAX; i++) { + if (!is_valid_cache(i)) + continue; + if (put_user(val | i, uindices)) + return -EFAULT; + uindices++; + } + return 0; +} + static u64 cp15_to_index(const struct coproc_reg *reg) { u64 val = KVM_REG_ARM | (15 << KVM_REG_ARM_COPROC_SHIFT); @@ -649,6 +786,7 @@ static int walk_cp15(struct kvm_vcpu *vcpu, u64 __user *uind) unsigned long kvm_arm_num_coproc_regs(struct kvm_vcpu *vcpu) { return ARRAY_SIZE(invariant_cp15) + + num_demux_regs() + walk_cp15(vcpu, (u64 __user *)NULL); } @@ -665,9 +803,11 @@ int kvm_arm_copy_coproc_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) } err = walk_cp15(vcpu, uindices); - if (err > 0) - err = 0; - return err; + if (err < 0) + return err; + uindices += err; + + return write_demux_regids(uindices); } void kvm_coproc_table_init(void) @@ -681,6 +821,23 @@ void kvm_coproc_table_init(void) /* We abuse the reset function to overwrite the table itself. */ for (i = 0; i < ARRAY_SIZE(invariant_cp15); i++) invariant_cp15[i].reset(NULL, &invariant_cp15[i]); + + /* + * CLIDR format is awkward, so clean it up. See ARM B4.1.20: + * + * If software reads the Cache Type fields from Ctype1 + * upwards, once it has seen a value of 0b000, no caches + * exist at further-out levels of the hierarchy. So, for + * example, if Ctype3 is the first Cache Type field with a + * value of 0b000, the values of Ctype4 to Ctype7 must be + * ignored. + */ + asm volatile("mrc p15, 1, %0, c0, c0, 1" : "=r" (cache_levels)); + for (i = 0; i < 7; i++) + if (((cache_levels >> (i*3)) & 7) == 0) + break; + /* Clear all higher bits. */ + cache_levels &= (1 << (i*3))-1; } /**