Re: [PATCH v4 01/66] arm64: Add ARM64_HAS_NESTED_VIRT cpufeature

On Thu, 20 May 2021 14:32:17 +0100,
Zenghui Yu [off-list ref] wrote:

On 2021/5/11 0:58, Marc Zyngier wrote:

quoted

From: Jintack Lim <redacted>

Add a new ARM64_HAS_NESTED_VIRT feature to indicate that the
CPU has the ARMv8.3 nested virtualization capability.

This will be used to support nested virtualization in KVM.

Signed-off-by: Jintack Lim <redacted>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Christoffer Dall <redacted>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 .../admin-guide/kernel-parameters.txt         |  4 +++
 arch/arm64/include/asm/cpucaps.h              |  1 +
 arch/arm64/kernel/cpufeature.c                | 25 +++++++++++++++++++
 3 files changed, 30 insertions(+)

[...]

quoted

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index efed2830d141..056de86d7f6f 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c

@@ -1645,6 +1645,21 @@ static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused)
 		write_sysreg(read_sysreg(tpidr_el1), tpidr_el2);
 }
 +static bool nested_param;
+static bool has_nested_virt_support(const struct arm64_cpu_capabilities *cap,
+				    int scope)
+{
+	return has_cpuid_feature(cap, scope) &&
+		nested_param;
+}

Nitpick:

How about putting them into a single line (they still perfectly
fit within the 80-colume limit)?

Fair enough.

	M.

-- 
Without deviation from the norm, progress is not possible.

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