linux-kernel - [PATCH v4 07/21] arm64/sme: Enable host kernel to access ZT0

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Message-Id: <20221208-arm64-sme2-v4-7-f2fa0aef982f@kernel.org>
Date:   Mon, 16 Jan 2023 16:04:42 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Oleg Nesterov <oleg@...hat.com>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Shuah Khan <shuah@...nel.org>
Cc:     Alan Hayward <alan.hayward@....com>,
        Luis Machado <luis.machado@....com>,
        Szabolcs Nagy <szabolcs.nagy@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvmarm@...ts.linux.dev, linux-kselftest@...r.kernel.org,
        Mark Brown <broonie@...nel.org>
Subject: [PATCH v4 07/21] arm64/sme: Enable host kernel to access ZT0

The new register ZT0 introduced by SME2 comes with a new trap, disable it
for the host kernel so that we can implement support for it.

Signed-off-by: Mark Brown <broonie@...nel.org>
---
 arch/arm64/kernel/hyp-stub.S       | 6 ++++++
 arch/arm64/kernel/idreg-override.c | 1 +
 2 files changed, 7 insertions(+)

diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
index 2ee18c860f2a..d31d1acb170d 100644
--- a/arch/arm64/kernel/hyp-stub.S
+++ b/arch/arm64/kernel/hyp-stub.S
@@ -132,6 +132,12 @@ SYM_CODE_START_LOCAL(__finalise_el2)
 	orr	x0, x0, SMCR_ELx_FA64_MASK
 .Lskip_sme_fa64:
 
+	// ZT0 available?
+	__check_override id_aa64smfr0 ID_AA64SMFR0_EL1_SMEver_SHIFT 4 .Linit_sme_zt0 .Lskip_sme_zt0
+.Linit_sme_zt0:
+	orr	x0, x0, SMCR_ELx_EZT0_MASK
+.Lskip_sme_zt0:
+
 	orr	x0, x0, #SMCR_ELx_LEN_MASK	// Enable full SME vector
 	msr_s	SYS_SMCR_EL2, x0		// length for EL1.
 
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 95133765ed29..d833d78a7f31 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -131,6 +131,7 @@ static const struct ftr_set_desc smfr0 __initconst = {
 	.name		= "id_aa64smfr0",
 	.override	= &id_aa64smfr0_override,
 	.fields		= {
+		FIELD("smever", ID_AA64SMFR0_EL1_SMEver_SHIFT, NULL),
 		/* FA64 is a one bit field... :-/ */
 		{ "fa64", ID_AA64SMFR0_EL1_FA64_SHIFT, 1, },
 		{}

-- 
2.34.1