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From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org
Subject: [PATCH 6/8] kvm: replace __KVM_HAVE_READONLY_MEM with Kconfig symbol
Date: Wed, 31 Jan 2024 18:30:54 -0500
Message-Id: <20240131233056.10845-7-pbonzini@redhat.com>
In-Reply-To: <20240131233056.10845-1-pbonzini@redhat.com>
References: <20240131233056.10845-1-pbonzini@redhat.com>
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KVM uses __KVM_HAVE_* symbols in the architecture-dependent uapi/asm/kvm.h to mask
unused definitions in include/uapi/linux/kvm.h.  __KVM_HAVE_READONLY_MEM however
was nothing but a misguided attempt to define KVM_CAP_READONLY_MEM only on
architectures where KVM_CHECK_EXTENSION(KVM_CAP_READONLY_MEM) could possibly
return nonzero.  This however does not make sense, and it prevented userspace
from supporting this architecture-independent feature without recompilation.

Therefore, these days __KVM_HAVE_READONLY_MEM does not mask anything and
is only used in virt/kvm/kvm_main.c.  Userspace does not need to test it
and there should be no need for it to exist.  Remove it and replace it
with a Kconfig symbol within Linux source code.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/arm64/include/uapi/asm/kvm.h     | 1 -
 arch/arm64/kvm/Kconfig                | 1 +
 arch/loongarch/include/uapi/asm/kvm.h | 2 --
 arch/loongarch/kvm/Kconfig            | 1 +
 arch/mips/include/uapi/asm/kvm.h      | 2 --
 arch/mips/kvm/Kconfig                 | 1 +
 arch/riscv/include/uapi/asm/kvm.h     | 1 -
 arch/riscv/kvm/Kconfig                | 1 +
 arch/x86/include/uapi/asm/kvm.h       | 1 -
 arch/x86/kvm/Kconfig                  | 1 +
 include/uapi/linux/kvm.h              | 7 +++++++
 virt/kvm/Kconfig                      | 3 +++
 virt/kvm/kvm_main.c                   | 2 +-
 13 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 75809c8dc2f0..9c1040dad4eb 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -39,7 +39,6 @@
 
 #define __KVM_HAVE_GUEST_DEBUG
 #define __KVM_HAVE_IRQ_LINE
-#define __KVM_HAVE_READONLY_MEM
 #define __KVM_HAVE_VCPU_EVENTS
 
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 99193d3b8312..01398d2996c7 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -34,6 +34,7 @@ menuconfig KVM
 	select HAVE_KVM_IRQCHIP
 	select HAVE_KVM_IRQ_ROUTING
 	select HAVE_KVM_IRQ_BYPASS
+	select HAVE_KVM_READONLY_MEM
 	select HAVE_KVM_VCPU_RUN_PID_CHANGE
 	select SCHED_INFO
 	select GUEST_PERF_EVENTS if PERF_EVENTS
diff --git a/arch/loongarch/include/uapi/asm/kvm.h b/arch/loongarch/include/uapi/asm/kvm.h
index 923d0bd38294..109785922cf9 100644
--- a/arch/loongarch/include/uapi/asm/kvm.h
+++ b/arch/loongarch/include/uapi/asm/kvm.h
@@ -14,8 +14,6 @@
  * Some parts derived from the x86 version of this file.
  */
 
-#define __KVM_HAVE_READONLY_MEM
-
 #define KVM_COALESCED_MMIO_PAGE_OFFSET	1
 #define KVM_DIRTY_LOG_PAGE_OFFSET	64
 
diff --git a/arch/loongarch/kvm/Kconfig b/arch/loongarch/kvm/Kconfig
index ac4de790dc31..c4ef2b4d9797 100644
--- a/arch/loongarch/kvm/Kconfig
+++ b/arch/loongarch/kvm/Kconfig
@@ -27,6 +27,7 @@ config KVM
 	select KVM_GENERIC_HARDWARE_ENABLING
 	select KVM_GENERIC_MMU_NOTIFIER
 	select KVM_MMIO
+	select HAVE_KVM_READONLY_MEM
 	select KVM_XFER_TO_GUEST_WORK
 	help
 	  Support hosting virtualized guest machines using
diff --git a/arch/mips/include/uapi/asm/kvm.h b/arch/mips/include/uapi/asm/kvm.h
index edcf717c4327..9673dc9cb315 100644
--- a/arch/mips/include/uapi/asm/kvm.h
+++ b/arch/mips/include/uapi/asm/kvm.h
@@ -20,8 +20,6 @@
  * Some parts derived from the x86 version of this file.
  */
 
-#define __KVM_HAVE_READONLY_MEM
-
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
 
 /*
diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
index 8916b3ed0f90..ab57221fa4dd 100644
--- a/arch/mips/kvm/Kconfig
+++ b/arch/mips/kvm/Kconfig
@@ -26,6 +26,7 @@ config KVM
 	select KVM_MMIO
 	select KVM_GENERIC_MMU_NOTIFIER
 	select KVM_GENERIC_HARDWARE_ENABLING
+	select HAVE_KVM_READONLY_MEM
 	help
 	  Support for hosting Guest kernels.
 
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 7499e88a947c..fdf4ba066131 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -16,7 +16,6 @@
 #include <asm/ptrace.h>
 
 #define __KVM_HAVE_IRQ_LINE
-#define __KVM_HAVE_READONLY_MEM
 
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
 
diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
index d490db943858..26d1727f0550 100644
--- a/arch/riscv/kvm/Kconfig
+++ b/arch/riscv/kvm/Kconfig
@@ -24,6 +24,7 @@ config KVM
 	select HAVE_KVM_IRQ_ROUTING
 	select HAVE_KVM_MSI
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
+	select HAVE_KVM_READONLY_MEM
 	select KVM_COMMON
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select KVM_GENERIC_HARDWARE_ENABLING
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index bf68e56fd484..c5e682ee7726 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -51,7 +51,6 @@
 #define __KVM_HAVE_DEBUGREGS
 #define __KVM_HAVE_XSAVE
 #define __KVM_HAVE_XCRS
-#define __KVM_HAVE_READONLY_MEM
 
 /* Architectural interrupt line count. */
 #define KVM_NR_INTERRUPTS 256
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 5692393b7565..d43efae05794 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -29,6 +29,7 @@ config KVM
 	select HAVE_KVM_DIRTY_RING_ACQ_REL
 	select HAVE_KVM_IRQ_BYPASS
 	select HAVE_KVM_IRQ_ROUTING
+	select HAVE_KVM_READONLY_MEM
 	select KVM_ASYNC_PF
 	select USER_RETURN_NOTIFIER
 	select KVM_MMIO
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index aa8a7ee0f554..29b73eedfe74 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -52,6 +52,9 @@ config KVM_ASYNC_PF_SYNC
 config HAVE_KVM_MSI
        bool
 
+config HAVE_KVM_READONLY_MEM
+       bool
+
 config HAVE_KVM_CPU_RELAX_INTERCEPT
        bool
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 10bfc88a69f7..ff588677beb7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1614,7 +1614,7 @@ static int check_memory_region_flags(struct kvm *kvm,
 	if (mem->flags & KVM_MEM_GUEST_MEMFD)
 		valid_flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
 
-#ifdef __KVM_HAVE_READONLY_MEM
+#ifdef CONFIG_HAVE_KVM_READONLY_MEM
 	valid_flags |= KVM_MEM_READONLY;
 #endif
 
-- 
2.39.0