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From: Marc Zyngier <marc.zyngier@arm.com>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>
Cc: Andre Przywara <andre.przywara@arm.com>,
	Andrew Murray <andrew.murray@arm.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Eric Auger <eric.auger@redhat.com>,
	James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry@arm.com>,
	Steven Price <steven.price@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 03/18] KVM: arm64: Make indirect vectors preamble behaviour symmetric
Date: Tue,  9 Jul 2019 13:24:52 +0100	[thread overview]
Message-ID: <20190709122507.214494-4-marc.zyngier@arm.com> (raw)
In-Reply-To: <20190709122507.214494-1-marc.zyngier@arm.com>

From: James Morse <james.morse@arm.com>

The KVM indirect vectors support is a little complicated. Different CPUs
may use different exception vectors for KVM that are generated at boot.
Adding new instructions involves checking all the possible combinations
do the right thing.

To make changes here easier to review lets state what we expect of the
preamble:
  1. The first vector run, must always run the preamble.
  2. Patching the head or tail of the vector shouldn't remove
     preamble instructions.

Today, this is easy as we only have one instruction in the preamble.
Change the unpatched tail of the indirect vector so that it always
runs this, regardless of patching.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/kvm/hyp/hyp-entry.S | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index 318a2f3996fc..a911b8ffc0f3 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -275,7 +275,7 @@ ENDPROC(__kvm_hyp_vector)
 /*
  * The default sequence is to directly branch to the KVM vectors,
  * using the computed offset. This applies for VHE as well as
- * !ARM64_HARDEN_EL2_VECTORS.
+ * !ARM64_HARDEN_EL2_VECTORS. The first vector must always run the preamble.
  *
  * For ARM64_HARDEN_EL2_VECTORS configurations, this gets replaced
  * with:
@@ -291,8 +291,8 @@ ENDPROC(__kvm_hyp_vector)
  * See kvm_patch_vector_branch for details.
  */
 alternative_cb	kvm_patch_vector_branch
-	b	__kvm_hyp_vector + (1b - 0b)
-	nop
+	stp	x0, x1, [sp, #-16]!
+	b	__kvm_hyp_vector + (1b - 0b + KVM_VECTOR_PREAMBLE)
 	nop
 	nop
 	nop
-- 
2.20.1


  parent reply	other threads:[~2019-07-09 12:25 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-09 12:24 [GIT PULL] KVM/arm updates for Linux 5.3 Marc Zyngier
2019-07-09 12:24 ` [PATCH 01/18] arm64: assembler: Switch ESB-instruction with a vanilla nop if !ARM64_HAS_RAS Marc Zyngier
2019-07-09 12:24 ` [PATCH 02/18] KVM: arm64: Abstract the size of the HYP vectors pre-amble Marc Zyngier
2019-07-09 12:24 ` Marc Zyngier [this message]
2019-07-09 12:24 ` [PATCH 04/18] KVM: arm64: Consume pending SError as early as possible Marc Zyngier
2019-07-09 12:24 ` [PATCH 05/18] KVM: arm64: Defer guest entry when an asynchronous exception is pending Marc Zyngier
2019-07-09 12:24 ` [PATCH 06/18] arm64: Update silicon-errata.txt for Neoverse-N1 #1349291 Marc Zyngier
2019-07-09 12:24 ` [PATCH 07/18] KVM: arm64: Re-mask SError after the one instruction window Marc Zyngier
2019-07-09 12:24 ` [PATCH 08/18] KVM: arm64: Skip more of the SError vaxorcism Marc Zyngier
2019-07-09 12:24 ` [PATCH 09/18] KVM: arm/arm64: Rename kvm_pmu_{enable/disable}_counter functions Marc Zyngier
2019-07-09 12:24 ` [PATCH 10/18] KVM: arm/arm64: Extract duplicated code to own function Marc Zyngier
2019-07-09 12:25 ` [PATCH 11/18] KVM: arm/arm64: Re-create event when setting counter value Marc Zyngier
2019-07-09 12:25 ` [PATCH 12/18] KVM: arm/arm64: Remove pmc->bitmask Marc Zyngier
2019-07-09 12:25 ` [PATCH 13/18] KVM: arm/arm64: Support chained PMU counters Marc Zyngier
2019-07-09 12:25 ` [PATCH 14/18] arm64: KVM: Propagate full Spectre v2 workaround state to KVM guests Marc Zyngier
2019-07-09 12:25 ` [PATCH 15/18] KVM: arm/arm64: Add save/restore support for firmware workaround state Marc Zyngier
2019-07-09 12:25 ` [PATCH 16/18] KVM: doc: Add API documentation on the KVM_REG_ARM_WORKAROUNDS register Marc Zyngier
2019-07-09 12:25 ` [PATCH 17/18] KVM: arm64: Migrate _elx sysreg accessors to msr_s/mrs_s Marc Zyngier
2019-07-09 12:25 ` [PATCH 18/18] KVM: arm/arm64: Initialise host's MPIDRs by reading the actual register Marc Zyngier
2019-07-11 13:40 ` [GIT PULL] KVM/arm updates for Linux 5.3 Paolo Bonzini

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