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>

Author: akihikodaki

arch/arm64/include/asm/cache.h

@@ -22,6 +22,9 @@
 #define CLIDR_CTYPE(clidr, level)	\
 	(((clidr) & CLIDR_CTYPE_MASK(level)) >> CLIDR_CTYPE_SHIFT(level))
 
+/* Ttypen, bits [2(n - 1) + 34 : 2(n - 1) + 33], for n = 1 to 7 */
+#define CLIDR_TTYPE_SHIFT(level)	(2 * ((level) - 1) + CLIDR_EL1_Ttypen_SHIFT)
+
 /*
  * Memory returned by kmalloc() may be used for DMA, so we must make
  * sure that all such allocations are cache aligned. Otherwise,

arch/arm64/include/asm/kvm_host.h

@@ -252,6 +252,7 @@ struct kvm_vcpu_fault_info {
 enum vcpu_sysreg {
 	__INVALID_SYSREG__,   /* 0 is reserved as an invalid value */
 	MPIDR_EL1,	/* MultiProcessor Affinity Register */
+	CLIDR_EL1,	/* Cache Level ID Register */
 	CSSELR_EL1,	/* Cache Size Selection Register */
 	SCTLR_EL1,	/* System Control Register */
 	ACTLR_EL1,	/* Auxiliary Control Register */
@@ -501,6 +502,9 @@ struct kvm_vcpu_arch {
 		u64 last_steal;
 		gpa_t base;
 	} steal;
+
+	/* Per-vcpu CCSIDR override or NULL */
+	u32 *ccsidr;
 };
 
 /*

arch/arm64/kvm/reset.c

@@ -157,6 +157,7 @@ void kvm_arm_vcpu_destroy(struct kvm_vcpu *vcpu)
 	if (sve_state)
 		kvm_unshare_hyp(sve_state, sve_state + vcpu_sve_state_size(vcpu));
 	kfree(sve_state);
+	kfree(vcpu->arch.ccsidr);
 }
 
 static void kvm_vcpu_reset_sve(struct kvm_vcpu *vcpu)