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From: Julien Grall <julien.grall@arm.com>
To: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu
Cc: marc.zyngier@arm.com, catalin.marinas@arm.com,
	will.deacon@arm.com, Julien Grall <julien.grall@arm.com>
Subject: [PATCH v3 14/15] arch/arm64: Introduce a capability to tell whether 16-bit VMID is available
Date: Wed, 24 Jul 2019 17:25:33 +0100	[thread overview]
Message-ID: <20190724162534.7390-15-julien.grall@arm.com> (raw)
In-Reply-To: <20190724162534.7390-1-julien.grall@arm.com>

At the moment, the function kvm_get_vmid_bits() is looking up for the
sanitized value of ID_AA64MMFR1_EL1 and extract the information
regarding the number of VMID bits supported.

This is fine as the function is mainly used during VMID roll-over. New
use in a follow-up patch will require the function to be called a every
context switch so we want the function to be more efficient.

A new capability is introduced to tell whether 16-bit VMID is
available.

Signed-off-by: Julien Grall <julien.grall@arm.com>

---
    Changes in v3:
        - Patch added
---
 arch/arm64/include/asm/cpucaps.h | 3 ++-
 arch/arm64/include/asm/kvm_mmu.h | 4 +---
 arch/arm64/kernel/cpufeature.c   | 9 +++++++++
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index f19fe4b9acc4..af8ab758b252 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -52,7 +52,8 @@
 #define ARM64_HAS_IRQ_PRIO_MASKING		42
 #define ARM64_HAS_DCPODP			43
 #define ARM64_WORKAROUND_1463225		44
+#define ARM64_HAS_16BIT_VMID			45
 
-#define ARM64_NCAPS				45
+#define ARM64_NCAPS				46
 
 #endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index befe37d4bc0e..2ce8055a84b8 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -413,9 +413,7 @@ static inline void __kvm_extend_hypmap(pgd_t *boot_hyp_pgd,
 
 static inline unsigned int kvm_get_vmid_bits(void)
 {
-	int reg = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
-
-	return (cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR1_VMIDBITS_SHIFT) == 2) ? 16 : 8;
+	return cpus_have_const_cap(ARM64_HAS_16BIT_VMID) ? 16 : 8;
 }
 
 /*
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index f29f36a65175..b401e56af35a 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1548,6 +1548,15 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.min_field_value = 1,
 	},
 #endif
+	{
+		.capability = ARM64_HAS_16BIT_VMID,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.sys_reg = SYS_ID_AA64MMFR1_EL1,
+		.field_pos = ID_AA64MMFR1_VMIDBITS_SHIFT,
+		.sign = FTR_UNSIGNED,
+		.min_field_value = ID_AA64MMFR1_VMIDBITS_16,
+		.matches = has_cpuid_feature,
+	},
 	{},
 };
 
-- 
2.11.0

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  parent reply	other threads:[~2019-07-24 16:26 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-24 16:25 [PATCH v3 00/15] kvm/arm: Align the VMID allocation with the arm64 ASID one Julien Grall
2019-07-24 16:25 ` [PATCH v3 01/15] arm64/mm: Introduce asid_info structure and move asid_generation/asid_map to it Julien Grall
2019-07-24 16:25 ` [PATCH v3 02/15] arm64/mm: Move active_asids and reserved_asids to asid_info Julien Grall
2019-07-24 16:25 ` [PATCH v3 03/15] arm64/mm: Move bits " Julien Grall
2019-07-24 16:25 ` [PATCH v3 04/15] arm64/mm: Move the variable lock and tlb_flush_pending " Julien Grall
2019-07-24 16:25 ` [PATCH v3 05/15] arm64/mm: Remove dependency on MM in new_context Julien Grall
2019-07-24 16:25 ` [PATCH v3 06/15] arm64/mm: Store the number of asid allocated per context Julien Grall
2019-07-24 16:25 ` [PATCH v3 07/15] arm64/mm: Introduce NUM_ASIDS Julien Grall
2019-07-24 16:25 ` [PATCH v3 08/15] arm64/mm: Split asid_inits in 2 parts Julien Grall
2019-07-24 16:25 ` [PATCH v3 09/15] arm64/mm: Split the function check_and_switch_context in 3 parts Julien Grall
2019-07-25 16:28   ` Catalin Marinas
2019-07-24 16:25 ` [PATCH v3 10/15] arm64/mm: Introduce a callback to flush the local context Julien Grall
2019-07-24 16:25 ` [PATCH v3 11/15] arm64: Move the ASID allocator code in a separate file Julien Grall
2019-07-24 16:25 ` [PATCH v3 12/15] arm64/lib: Add an helper to free memory allocated by the ASID allocator Julien Grall
2019-07-24 16:25 ` [PATCH v3 13/15] arm/kvm: Introduce a new VMID allocator Julien Grall
2019-07-24 16:25 ` Julien Grall [this message]
2019-07-24 16:25 ` [PATCH v3 15/15] kvm/arm: Align the VMID allocation with the arm64 ASID one Julien Grall

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