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From: Andrew Jones <ajones@ventanamicro.com>
To: linux-riscv@lists.infradead.org, kvm-riscv@lists.infradead.org,
	devicetree@vger.kernel.org
Cc: 'Anup Patel ' <apatel@ventanamicro.com>,
	'Palmer Dabbelt ' <palmer@dabbelt.com>,
	'Paul Walmsley ' <paul.walmsley@sifive.com>,
	'Krzysztof Kozlowski ' <krzysztof.kozlowski+dt@linaro.org>,
	'Atish Patra ' <atishp@rivosinc.com>,
	'Heiko Stuebner ' <heiko@sntech.de>,
	'Jisheng Zhang ' <jszhang@kernel.org>,
	'Rob Herring ' <robh@kernel.org>,
	'Albert Ou ' <aou@eecs.berkeley.edu>,
	'Conor Dooley ' <conor.dooley@microchip.com>
Subject: [PATCH v4 5/8] RISC-V: cpufeature: Put vendor_id to work
Date: Thu,  9 Feb 2023 16:26:25 +0100	[thread overview]
Message-ID: <20230209152628.129914-6-ajones@ventanamicro.com> (raw)
In-Reply-To: <20230209152628.129914-1-ajones@ventanamicro.com>

When [ab]using alternatives as cpufeature "static keys", which can
be used in assembly, also put vendor_id to work as application-
specific data. This will be initially used in Zicboz's application to
clear_page(), as Zicboz's block size must also be considered. In that
case, vendor_id's role will be to convey the maximum block size which
the Zicboz clear_page() implementation supports.

cpufeature alternative applications which need to check for the
existence or absence of other cpufeatures may also be able to make
use of this.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
---
 arch/riscv/kernel/cpufeature.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 0d2db03cf167..74736b4f0624 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -278,6 +278,11 @@ void __init riscv_fill_hwcap(void)
 }
 
 #ifdef CONFIG_RISCV_ALTERNATIVE
+static bool riscv_cpufeature_application_check(u32 feature, u16 data)
+{
+	return data == 0;
+}
+
 void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
 						  struct alt_entry *end,
 						  unsigned int stage)
@@ -289,8 +294,6 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
 		return;
 
 	for (alt = begin; alt < end; alt++) {
-		if (alt->vendor_id != 0)
-			continue;
 		if (alt->errata_id >= RISCV_ISA_EXT_MAX) {
 			WARN(1, "This extension id:%d is not in ISA extension list",
 				alt->errata_id);
@@ -300,6 +303,9 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
 		if (!__riscv_isa_extension_available(NULL, alt->errata_id))
 			continue;
 
+		if (!riscv_cpufeature_application_check(alt->errata_id, alt->vendor_id))
+			continue;
+
 		oldptr = ALT_OLD_PTR(alt);
 		altptr = ALT_ALT_PTR(alt);
 		patch_text_nosync(oldptr, altptr, alt->alt_len);
-- 
2.39.1


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  parent reply	other threads:[~2023-02-09 15:27 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-09 15:26 [PATCH v4 0/8] RISC-V: Apply Zicboz to clear_page Andrew Jones
2023-02-09 15:26 ` [PATCH v4 1/8] RISC-V: alternatives: Support patching multiple insns in assembly Andrew Jones
2023-02-09 18:02   ` Conor Dooley
2023-02-09 15:26 ` [PATCH v4 2/8] RISC-V: Factor out body of riscv_init_cbom_blocksize loop Andrew Jones
2023-02-09 15:26 ` [PATCH v4 3/8] dt-bindings: riscv: Document cboz-block-size Andrew Jones
2023-02-09 15:26 ` [PATCH v4 4/8] RISC-V: Add Zicboz detection and block size parsing Andrew Jones
2023-02-09 15:26 ` Andrew Jones [this message]
2023-02-09 19:04   ` [PATCH v4 5/8] RISC-V: cpufeature: Put vendor_id to work Conor Dooley
2023-02-10  7:58     ` Andrew Jones
2023-02-10 20:29       ` Conor Dooley
2023-02-12 16:26         ` Andrew Jones
2023-02-09 15:26 ` [PATCH v4 6/8] RISC-V: Use Zicboz in clear_page when available Andrew Jones
2023-02-09 19:09   ` Conor Dooley
2023-02-10  8:05     ` Andrew Jones
2023-02-10  9:04       ` Conor Dooley
2023-02-17 10:18   ` Ben Dooks
2023-02-17 10:50     ` Ben Dooks
2023-02-17 12:29       ` Andrew Jones
2023-02-20 18:43         ` Ben Dooks
2023-02-20 19:24           ` Andrew Jones
2023-02-17 12:44     ` Andrew Jones
2023-02-09 15:26 ` [PATCH v4 7/8] RISC-V: KVM: Provide UAPI for Zicboz block size Andrew Jones
2023-02-09 15:26 ` [PATCH v4 8/8] RISC-V: KVM: Expose Zicboz to the guest Andrew Jones
2023-02-09 17:45 ` [PATCH v4 0/8] RISC-V: Apply Zicboz to clear_page Conor Dooley

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