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From: David Brazdil <dbrazdil@google.com>
To: kvmarm@lists.cs.columbia.edu
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, kernel-team@android.com,
	Jamie Iles <jamie@nuviainc.com>,
	David Brazdil <dbrazdil@google.com>
Subject: [PATCH 1/9] KVM: arm64: Correctly align nVHE percpu data
Date: Wed,  9 Dec 2020 13:17:38 +0000	[thread overview]
Message-ID: <20201209131746.85622-2-dbrazdil@google.com> (raw)
In-Reply-To: <20201209131746.85622-1-dbrazdil@google.com>

From: Jamie Iles <jamie@nuviainc.com>

The nVHE percpu data is partially linked but the nVHE linker script did
not align the percpu section.  The PERCPU_INPUT macro would then align
the data to a page boundary:

  #define PERCPU_INPUT(cacheline)					\
  	__per_cpu_start = .;						\
  	*(.data..percpu..first)						\
  	. = ALIGN(PAGE_SIZE);						\
  	*(.data..percpu..page_aligned)					\
  	. = ALIGN(cacheline);						\
  	*(.data..percpu..read_mostly)					\
  	. = ALIGN(cacheline);						\
  	*(.data..percpu)						\
  	*(.data..percpu..shared_aligned)				\
  	PERCPU_DECRYPTED_SECTION					\
  	__per_cpu_end = .;

but then when the final vmlinux linking happens the hypervisor percpu
data is included after page alignment and so the offsets potentially
don't match.  On my build I saw that the .hyp.data..percpu section was
at address 0x20 and then the percpu data would begin at 0x1000 (because
of the page alignment in PERCPU_INPUT), but when linked into vmlinux,
everything would be shifted down by 0x20 bytes.

This manifests as one of the CPUs getting lost when running
kvm-unit-tests or starting any VM and subsequent soft lockup on a Cortex
A72 device.

Fixes: 30c953911c43 ("kvm: arm64: Set up hyp percpu data for nVHE")
Signed-off-by: Jamie Iles <jamie@nuviainc.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Cc: David Brazdil <dbrazdil@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201113150406.14314-1-jamie@nuviainc.com
---
 arch/arm64/kvm/hyp/nvhe/hyp.lds.S | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
index 5d76ff2ba63e..1206d0d754d5 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
@@ -13,6 +13,11 @@
 
 SECTIONS {
 	HYP_SECTION(.text)
+	/*
+	 * .hyp..data..percpu needs to be page aligned to maintain the same
+	 * alignment for when linking into vmlinux.
+	 */
+	. = ALIGN(PAGE_SIZE);
 	HYP_SECTION_NAME(.data..percpu) : {
 		PERCPU_INPUT(L1_CACHE_BYTES)
 	}
-- 
2.29.2.576.ga3fc446d84-goog


  reply	other threads:[~2020-12-09 13:20 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-09 13:17 [PATCH 0/9] KVM: arm64: Relocate absolute hyp VAs David Brazdil
2020-12-09 13:17 ` David Brazdil [this message]
2020-12-09 13:17 ` [PATCH 2/9] KVM: arm64: Rename .idmap.text in hyp linker script David Brazdil
2020-12-09 13:17 ` [PATCH 3/9] KVM: arm64: Set up .hyp.rodata ELF section David Brazdil
2020-12-09 13:17 ` [PATCH 4/9] KVM: arm64: Add symbol at the beginning of each hyp section David Brazdil
2020-12-09 13:17 ` [PATCH 5/9] KVM: arm64: Generate hyp relocation data David Brazdil
2020-12-09 13:17 ` [PATCH 6/9] KVM: arm64: Apply hyp relocations at runtime David Brazdil
2020-12-09 13:17 ` [PATCH 7/9] KVM: arm64: Fix constant-pool users in hyp David Brazdil
2020-12-09 13:17 ` [PATCH 8/9] KVM: arm64: Remove patching of fn pointers " David Brazdil
2020-12-09 13:17 ` [PATCH 9/9] KVM: arm64: Remove hyp_symbol_addr David Brazdil

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