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KVM: arm64: Normalize cache configuration
Before this change, the cache configuration of the physical CPU was exposed to vcpus. This is problematic because the cache configuration a vcpu sees varies when it migrates between vcpus with different cache configurations. Fabricate cache configuration from the sanitized value, which holds the CTR_EL0 value the userspace sees regardless of which physical CPU it resides on. CLIDR_EL1 and CCSIDR_EL1 are now writable from the userspace so that the VMM can restore the values saved with the old kernel. Suggested-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> Link: https://lore.kernel.org/r/20230112023852.42012-8-akihiko.odaki@daynix.com [ Oliver: Squash Marc's fix for CCSIDR_EL1.LineSize when set from userspace ] Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Akihiko Odaki
Oliver Upton
parent
bf48040cd9
commit
7af0c2534f
@ -22,6 +22,9 @@
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#define CLIDR_CTYPE(clidr, level) \
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(((clidr) & CLIDR_CTYPE_MASK(level)) >> CLIDR_CTYPE_SHIFT(level))
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/* Ttypen, bits [2(n - 1) + 34 : 2(n - 1) + 33], for n = 1 to 7 */
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#define CLIDR_TTYPE_SHIFT(level) (2 * ((level) - 1) + CLIDR_EL1_Ttypen_SHIFT)
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/*
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* Memory returned by kmalloc() may be used for DMA, so we must make
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* sure that all such allocations are cache aligned. Otherwise,
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@ -252,6 +252,7 @@ struct kvm_vcpu_fault_info {
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enum vcpu_sysreg {
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__INVALID_SYSREG__, /* 0 is reserved as an invalid value */
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MPIDR_EL1, /* MultiProcessor Affinity Register */
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CLIDR_EL1, /* Cache Level ID Register */
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CSSELR_EL1, /* Cache Size Selection Register */
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SCTLR_EL1, /* System Control Register */
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ACTLR_EL1, /* Auxiliary Control Register */
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@ -501,6 +502,9 @@ struct kvm_vcpu_arch {
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u64 last_steal;
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gpa_t base;
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} steal;
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/* Per-vcpu CCSIDR override or NULL */
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u32 *ccsidr;
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};
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/*
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@ -157,6 +157,7 @@ void kvm_arm_vcpu_destroy(struct kvm_vcpu *vcpu)
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if (sve_state)
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kvm_unshare_hyp(sve_state, sve_state + vcpu_sve_state_size(vcpu));
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kfree(sve_state);
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kfree(vcpu->arch.ccsidr);
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}
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static void kvm_vcpu_reset_sve(struct kvm_vcpu *vcpu)
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@ -11,6 +11,7 @@
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#include <linux/bitfield.h>
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#include <linux/bsearch.h>
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#include <linux/cacheinfo.h>
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#include <linux/kvm_host.h>
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#include <linux/mm.h>
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#include <linux/printk.h>
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@ -81,25 +82,97 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg)
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__vcpu_sys_reg(vcpu, reg) = val;
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}
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/* 3 bits per cache level, as per CLIDR, but non-existent caches always 0 */
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static u32 cache_levels;
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/* CSSELR values; used to index KVM_REG_ARM_DEMUX_ID_CCSIDR */
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#define CSSELR_MAX 14
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/* Which cache CCSIDR represents depends on CSSELR value. */
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static u32 get_ccsidr(u32 csselr)
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/*
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* Returns the minimum line size for the selected cache, expressed as
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* Log2(bytes).
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*/
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static u8 get_min_cache_line_size(bool icache)
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{
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u32 ccsidr;
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u64 ctr = read_sanitised_ftr_reg(SYS_CTR_EL0);
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u8 field;
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/* Make sure noone else changes CSSELR during this! */
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local_irq_disable();
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write_sysreg(csselr, csselr_el1);
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isb();
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ccsidr = read_sysreg(ccsidr_el1);
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local_irq_enable();
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if (icache)
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field = SYS_FIELD_GET(CTR_EL0, IminLine, ctr);
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else
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field = SYS_FIELD_GET(CTR_EL0, DminLine, ctr);
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return ccsidr;
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/*
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* Cache line size is represented as Log2(words) in CTR_EL0.
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* Log2(bytes) can be derived with the following:
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*
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* Log2(words) + 2 = Log2(bytes / 4) + 2
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* = Log2(bytes) - 2 + 2
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* = Log2(bytes)
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*/
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return field + 2;
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}
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/* Which cache CCSIDR represents depends on CSSELR value. */
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static u32 get_ccsidr(struct kvm_vcpu *vcpu, u32 csselr)
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{
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u8 line_size;
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if (vcpu->arch.ccsidr)
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return vcpu->arch.ccsidr[csselr];
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line_size = get_min_cache_line_size(csselr & CSSELR_EL1_InD);
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/*
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* Fabricate a CCSIDR value as the overriding value does not exist.
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* The real CCSIDR value will not be used as it can vary by the
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* physical CPU which the vcpu currently resides in.
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*
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* The line size is determined with get_min_cache_line_size(), which
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* should be valid for all CPUs even if they have different cache
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* configuration.
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*
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* The associativity bits are cleared, meaning the geometry of all data
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* and unified caches (which are guaranteed to be PIPT and thus
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* non-aliasing) are 1 set and 1 way.
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* Guests should not be doing cache operations by set/way at all, and
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* for this reason, we trap them and attempt to infer the intent, so
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* that we can flush the entire guest's address space at the appropriate
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* time. The exposed geometry minimizes the number of the traps.
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* [If guests should attempt to infer aliasing properties from the
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* geometry (which is not permitted by the architecture), they would
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* only do so for virtually indexed caches.]
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*
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* We don't check if the cache level exists as it is allowed to return
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* an UNKNOWN value if not.
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*/
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return SYS_FIELD_PREP(CCSIDR_EL1, LineSize, line_size - 4);
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}
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static int set_ccsidr(struct kvm_vcpu *vcpu, u32 csselr, u32 val)
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{
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u8 line_size = FIELD_GET(CCSIDR_EL1_LineSize, val) + 4;
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u32 *ccsidr = vcpu->arch.ccsidr;
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u32 i;
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if ((val & CCSIDR_EL1_RES0) ||
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line_size < get_min_cache_line_size(csselr & CSSELR_EL1_InD))
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return -EINVAL;
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if (!ccsidr) {
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if (val == get_ccsidr(vcpu, csselr))
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return 0;
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ccsidr = kmalloc_array(CSSELR_MAX, sizeof(u32), GFP_KERNEL);
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if (!ccsidr)
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return -ENOMEM;
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for (i = 0; i < CSSELR_MAX; i++)
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ccsidr[i] = get_ccsidr(vcpu, i);
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vcpu->arch.ccsidr = ccsidr;
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}
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ccsidr[csselr] = val;
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return 0;
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}
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/*
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@ -1391,10 +1464,78 @@ static bool access_clidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
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if (p->is_write)
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return write_to_read_only(vcpu, p, r);
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p->regval = read_sysreg(clidr_el1);
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p->regval = __vcpu_sys_reg(vcpu, r->reg);
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return true;
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}
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/*
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* Fabricate a CLIDR_EL1 value instead of using the real value, which can vary
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* by the physical CPU which the vcpu currently resides in.
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*/
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static void reset_clidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
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{
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u64 ctr_el0 = read_sanitised_ftr_reg(SYS_CTR_EL0);
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u64 clidr;
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u8 loc;
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if ((ctr_el0 & CTR_EL0_IDC)) {
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/*
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* Data cache clean to the PoU is not required so LoUU and LoUIS
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* will not be set and a unified cache, which will be marked as
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* LoC, will be added.
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*
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* If not DIC, let the unified cache L2 so that an instruction
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* cache can be added as L1 later.
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*/
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loc = (ctr_el0 & CTR_EL0_DIC) ? 1 : 2;
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clidr = CACHE_TYPE_UNIFIED << CLIDR_CTYPE_SHIFT(loc);
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} else {
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/*
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* Data cache clean to the PoU is required so let L1 have a data
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* cache and mark it as LoUU and LoUIS. As L1 has a data cache,
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* it can be marked as LoC too.
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*/
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loc = 1;
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clidr = 1 << CLIDR_LOUU_SHIFT;
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clidr |= 1 << CLIDR_LOUIS_SHIFT;
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clidr |= CACHE_TYPE_DATA << CLIDR_CTYPE_SHIFT(1);
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}
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/*
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* Instruction cache invalidation to the PoU is required so let L1 have
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* an instruction cache. If L1 already has a data cache, it will be
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* CACHE_TYPE_SEPARATE.
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*/
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if (!(ctr_el0 & CTR_EL0_DIC))
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clidr |= CACHE_TYPE_INST << CLIDR_CTYPE_SHIFT(1);
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clidr |= loc << CLIDR_LOC_SHIFT;
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/*
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* Add tag cache unified to data cache. Allocation tags and data are
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* unified in a cache line so that it looks valid even if there is only
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* one cache line.
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*/
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if (kvm_has_mte(vcpu->kvm))
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clidr |= 2 << CLIDR_TTYPE_SHIFT(loc);
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__vcpu_sys_reg(vcpu, r->reg) = clidr;
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}
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static int set_clidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
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u64 val)
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{
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u64 ctr_el0 = read_sanitised_ftr_reg(SYS_CTR_EL0);
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u64 idc = !CLIDR_LOC(val) || (!CLIDR_LOUIS(val) && !CLIDR_LOUU(val));
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if ((val & CLIDR_EL1_RES0) || (!(ctr_el0 & CTR_EL0_IDC) && idc))
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return -EINVAL;
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__vcpu_sys_reg(vcpu, rd->reg) = val;
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return 0;
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}
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static bool access_csselr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
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const struct sys_reg_desc *r)
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{
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@ -1416,22 +1557,10 @@ static bool access_ccsidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
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return write_to_read_only(vcpu, p, r);
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csselr = vcpu_read_sys_reg(vcpu, CSSELR_EL1);
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p->regval = get_ccsidr(csselr);
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csselr &= CSSELR_EL1_Level | CSSELR_EL1_InD;
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if (csselr < CSSELR_MAX)
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p->regval = get_ccsidr(vcpu, csselr);
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/*
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* Guests should not be doing cache operations by set/way at all, and
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* for this reason, we trap them and attempt to infer the intent, so
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* that we can flush the entire guest's address space at the appropriate
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* time.
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* To prevent this trapping from causing performance problems, let's
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* expose the geometry of all data and unified caches (which are
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* guaranteed to be PIPT and thus non-aliasing) as 1 set and 1 way.
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* [If guests should attempt to infer aliasing properties from the
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* geometry (which is not permitted by the architecture), they would
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* only do so for virtually indexed caches.]
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*/
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if (!(csselr & 1)) // data or unified cache
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p->regval &= ~GENMASK(27, 3);
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return true;
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}
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@ -1723,7 +1852,8 @@ static const struct sys_reg_desc sys_reg_descs[] = {
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{ SYS_DESC(SYS_CNTKCTL_EL1), NULL, reset_val, CNTKCTL_EL1, 0},
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{ SYS_DESC(SYS_CCSIDR_EL1), access_ccsidr },
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{ SYS_DESC(SYS_CLIDR_EL1), access_clidr },
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{ SYS_DESC(SYS_CLIDR_EL1), access_clidr, reset_clidr, CLIDR_EL1,
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.set_user = set_clidr },
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{ SYS_DESC(SYS_CCSIDR2_EL1), undef_access },
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{ SYS_DESC(SYS_SMIDR_EL1), undef_access },
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{ SYS_DESC(SYS_CSSELR_EL1), access_csselr, reset_unknown, CSSELR_EL1 },
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@ -2735,7 +2865,6 @@ id_to_sys_reg_desc(struct kvm_vcpu *vcpu, u64 id,
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FUNCTION_INVARIANT(midr_el1)
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FUNCTION_INVARIANT(revidr_el1)
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FUNCTION_INVARIANT(clidr_el1)
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FUNCTION_INVARIANT(aidr_el1)
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static void get_ctr_el0(struct kvm_vcpu *v, const struct sys_reg_desc *r)
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@ -2747,7 +2876,6 @@ static void get_ctr_el0(struct kvm_vcpu *v, const struct sys_reg_desc *r)
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static struct sys_reg_desc invariant_sys_regs[] = {
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{ SYS_DESC(SYS_MIDR_EL1), NULL, get_midr_el1 },
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{ SYS_DESC(SYS_REVIDR_EL1), NULL, get_revidr_el1 },
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{ SYS_DESC(SYS_CLIDR_EL1), NULL, get_clidr_el1 },
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{ SYS_DESC(SYS_AIDR_EL1), NULL, get_aidr_el1 },
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{ SYS_DESC(SYS_CTR_EL0), NULL, get_ctr_el0 },
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};
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@ -2784,33 +2912,7 @@ static int set_invariant_sys_reg(u64 id, u64 __user *uaddr)
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return 0;
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}
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static bool is_valid_cache(u32 val)
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{
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u32 level, ctype;
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if (val >= CSSELR_MAX)
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return false;
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/* Bottom bit is Instruction or Data bit. Next 3 bits are level. */
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level = (val >> 1);
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ctype = (cache_levels >> (level * 3)) & 7;
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switch (ctype) {
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case 0: /* No cache */
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return false;
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case 1: /* Instruction cache only */
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return (val & 1);
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case 2: /* Data cache only */
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case 4: /* Unified cache */
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return !(val & 1);
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case 3: /* Separate instruction and data caches */
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return true;
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default: /* Reserved: we can't know instruction or data. */
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return false;
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}
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}
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static int demux_c15_get(u64 id, void __user *uaddr)
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static int demux_c15_get(struct kvm_vcpu *vcpu, u64 id, void __user *uaddr)
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{
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u32 val;
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u32 __user *uval = uaddr;
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@ -2826,16 +2928,16 @@ static int demux_c15_get(u64 id, void __user *uaddr)
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return -ENOENT;
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val = (id & KVM_REG_ARM_DEMUX_VAL_MASK)
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>> KVM_REG_ARM_DEMUX_VAL_SHIFT;
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if (!is_valid_cache(val))
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if (val >= CSSELR_MAX)
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return -ENOENT;
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return put_user(get_ccsidr(val), uval);
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return put_user(get_ccsidr(vcpu, val), uval);
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default:
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return -ENOENT;
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}
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}
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static int demux_c15_set(u64 id, void __user *uaddr)
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static int demux_c15_set(struct kvm_vcpu *vcpu, u64 id, void __user *uaddr)
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{
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u32 val, newval;
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u32 __user *uval = uaddr;
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@ -2851,16 +2953,13 @@ static int demux_c15_set(u64 id, void __user *uaddr)
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return -ENOENT;
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val = (id & KVM_REG_ARM_DEMUX_VAL_MASK)
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>> KVM_REG_ARM_DEMUX_VAL_SHIFT;
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if (!is_valid_cache(val))
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if (val >= CSSELR_MAX)
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return -ENOENT;
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if (get_user(newval, uval))
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return -EFAULT;
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/* This is also invariant: you can't change it. */
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if (newval != get_ccsidr(val))
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return -EINVAL;
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return 0;
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return set_ccsidr(vcpu, val, newval);
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default:
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return -ENOENT;
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}
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@ -2897,7 +2996,7 @@ int kvm_arm_sys_reg_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
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int err;
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if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_DEMUX)
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return demux_c15_get(reg->id, uaddr);
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return demux_c15_get(vcpu, reg->id, uaddr);
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err = get_invariant_sys_reg(reg->id, uaddr);
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if (err != -ENOENT)
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@ -2941,7 +3040,7 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
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int err;
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if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_DEMUX)
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return demux_c15_set(reg->id, uaddr);
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return demux_c15_set(vcpu, reg->id, uaddr);
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err = set_invariant_sys_reg(reg->id, uaddr);
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if (err != -ENOENT)
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@ -2953,13 +3052,7 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
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static unsigned int num_demux_regs(void)
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{
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unsigned int i, count = 0;
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for (i = 0; i < CSSELR_MAX; i++)
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if (is_valid_cache(i))
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count++;
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return count;
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return CSSELR_MAX;
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}
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static int write_demux_regids(u64 __user *uindices)
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@ -2969,8 +3062,6 @@ static int write_demux_regids(u64 __user *uindices)
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val |= KVM_REG_ARM_DEMUX_ID_CCSIDR;
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for (i = 0; i < CSSELR_MAX; i++) {
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if (!is_valid_cache(i))
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continue;
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||||
if (put_user(val | i, uindices))
|
||||
return -EFAULT;
|
||||
uindices++;
|
||||
@ -3072,7 +3163,6 @@ int kvm_sys_reg_table_init(void)
|
||||
{
|
||||
bool valid = true;
|
||||
unsigned int i;
|
||||
struct sys_reg_desc clidr;
|
||||
|
||||
/* Make sure tables are unique and in order. */
|
||||
valid &= check_sysreg_table(sys_reg_descs, ARRAY_SIZE(sys_reg_descs), false);
|
||||
@ -3089,23 +3179,5 @@ int kvm_sys_reg_table_init(void)
|
||||
for (i = 0; i < ARRAY_SIZE(invariant_sys_regs); i++)
|
||||
invariant_sys_regs[i].reset(NULL, &invariant_sys_regs[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.
|
||||
*/
|
||||
get_clidr_el1(NULL, &clidr); /* Ugly... */
|
||||
cache_levels = clidr.val;
|
||||
for (i = 0; i < 7; i++)
|
||||
if (((cache_levels >> (i*3)) & 7) == 0)
|
||||
break;
|
||||
/* Clear all higher bits. */
|
||||
cache_levels &= (1 << (i*3))-1;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user