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From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	 Vitaly Kuznetsov <vkuznets@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Paul Durrant <paul@xen.org>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	 Yosry Ahmed <yosry@kernel.org>
Subject: [PATCH 08/11] KVM: x86: Drop non-raw kvm_<reg>_write() helpers
Date: Thu,  9 Apr 2026 16:56:19 -0700	[thread overview]
Message-ID: <20260409235622.2052730-9-seanjc@google.com> (raw)
In-Reply-To: <20260409235622.2052730-1-seanjc@google.com>

Drop the non-raw, mode-aware kvm_<reg>_write() helpers as there is no
usage in KVM, and in all likelihood there will never be usage in KVM as
use of hardcoded registers in instructions is uncommon, and *modifying*
hardcoded registers is practically unheard of.  While there are a few
instructions that modify registers in mode-aware ways, e.g. REP string
and some ENCLS varieties, the odds of KVM needing to emulate such
instructions (outside of the fully emulator) are vanishingly small.

Drop kvm_<reg>_write() to prevent incorrect usage; _if_ a new instruction
comes along that needs to modify a hardcoded register, this can be
reverted.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/x86.h | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 2550380fa79e..cebea89b296c 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -435,11 +435,6 @@ static __always_inline unsigned long kvm_##lname##_read(struct kvm_vcpu *vcpu)
 {											\
 	return vcpu->arch.regs[VCPU_REGS_##uname] & kvm_reg_mode_mask(vcpu);		\
 }											\
-static __always_inline void kvm_##lname##_write(struct kvm_vcpu *vcpu,			\
-						unsigned long val)			\
-{											\
-	vcpu->arch.regs[VCPU_REGS_##uname] = val & kvm_reg_mode_mask(vcpu);		\
-}											\
 static __always_inline unsigned long kvm_##lname##_read_raw(struct kvm_vcpu *vcpu)	\
 {											\
 	return vcpu->arch.regs[VCPU_REGS_##uname];					\
-- 
2.53.0.1213.gd9a14994de-goog


  parent reply	other threads:[~2026-04-09 23:56 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-09 23:56 [PATCH 00/11] KVM: x86: Clean up kvm_<reg>_{read,write}() mess Sean Christopherson
2026-04-09 23:56 ` [PATCH 01/11] KVM: SVM: Truncate INVLPGA address in compatibility mode Sean Christopherson
2026-04-09 23:56 ` [PATCH 02/11] KVM: x86/xen: Bug the VM if 32-bit KVM observes a 64-bit mode hypercall Sean Christopherson
2026-04-09 23:56 ` [PATCH 03/11] KVM: x86/xen: Don't truncate RAX when handling hypercall from protected guest Sean Christopherson
2026-04-09 23:56 ` [PATCH 04/11] KVM: VMX: Read 32-bit GPR values for ENCLS instructions outside of 64-bit mode Sean Christopherson
2026-04-09 23:56 ` [PATCH 05/11] KVM: x86: Trace hypercall register *after* truncating values for 32-bit Sean Christopherson
2026-04-09 23:56 ` [PATCH 06/11] KVM: x86: Move kvm_<reg>_{read,write}() definitions to x86.h Sean Christopherson
2026-04-09 23:56 ` [PATCH 07/11] KVM: x86: Add mode-aware versions of kvm_<reg>_{read,write}() helpers Sean Christopherson
2026-04-09 23:56 ` Sean Christopherson [this message]
2026-04-09 23:56 ` [PATCH 09/11] KVM: nSVM: Use kvm_rax_read() now that it's mode-aware Sean Christopherson
2026-04-09 23:56 ` [PATCH 10/11] Revert "KVM: VMX: Read 32-bit GPR values for ENCLS instructions outside of 64-bit mode" Sean Christopherson
2026-04-09 23:56 ` [PATCH 11/11] KVM: x86: Harden is_64_bit_hypercall() against bugs on 32-bit kernels Sean Christopherson

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