[RFC PATCH kvmtool v1 18/32] Pass the memory file descriptor and offset when registering ram

From: Fuad Tabba <tabba@google.com>
To: kvm@vger.kernel.org
Cc: julien.thierry.kdev@gmail.com, andre.przywara@arm.com,
	alexandru.elisei@arm.com, alex.bennee@linaro.org,
	will@kernel.org, tabba@google.com
Subject: [RFC PATCH kvmtool v1 18/32] Pass the memory file descriptor and offset when registering ram
Date: Fri,  2 Dec 2022 17:44:03 +0000	[thread overview]
Message-ID: <20221202174417.1310826-19-tabba@google.com> (raw)
In-Reply-To: <20221202174417.1310826-1-tabba@google.com>

Since the memory file descriptor is the canonical reference to guest
memory, pass that and the offset when registering guest memory.
Future fd-based kvm proposals might even not require a userspace
address [*].

No functional change intended.

Signed-off-by: Fuad Tabba <tabba@google.com>

[*] https://lore.kernel.org/all/20221202061347.1070246-1-chao.p.peng@linux.intel.com/
---
 arm/aarch64/pvtime.c |  2 +-
 arm/kvm.c            |  3 ++-
 hw/cfi_flash.c       |  4 +++-
 hw/vesa.c            |  2 +-
 include/kvm/kvm.h    | 17 +++++++++--------
 kvm.c                |  3 ++-
 mips/kvm.c           |  6 +++---
 powerpc/kvm.c        |  2 +-
 riscv/kvm.c          |  2 +-
 vfio/core.c          |  3 ++-
 x86/kvm.c            |  6 +++---
 11 files changed, 28 insertions(+), 22 deletions(-)

diff --git a/arm/aarch64/pvtime.c b/arm/aarch64/pvtime.c
index a7ba03e..9b06ee4 100644
--- a/arm/aarch64/pvtime.c
+++ b/arm/aarch64/pvtime.c
@@ -28,7 +28,7 @@ static int pvtime__alloc_region(struct kvm *kvm)
 	}
 
 	ret = kvm__register_ram(kvm, ARM_PVTIME_BASE,
-				ARM_PVTIME_SIZE, mem);
+				ARM_PVTIME_SIZE, mem, mem_fd, 0);
 	if (ret) {
 		munmap(mem, ARM_PVTIME_SIZE);
 		close(mem_fd);
diff --git a/arm/kvm.c b/arm/kvm.c
index 5cceef8..8772a55 100644
--- a/arm/kvm.c
+++ b/arm/kvm.c
@@ -50,7 +50,8 @@ void kvm__init_ram(struct kvm *kvm)
 	phys_start	= kvm->cfg.ram_addr;
 	phys_size	= kvm->ram_size;
 
-	err = kvm__register_ram(kvm, phys_start, phys_size, kvm->ram_start);
+	err = kvm__register_ram(kvm, phys_start, phys_size, kvm->ram_start,
+		kvm->ram_fd, 0);
 	if (err)
 		die("Failed to register %lld bytes of memory at physical "
 		    "address 0x%llx [err %d]", phys_size, phys_start, err);
diff --git a/hw/cfi_flash.c b/hw/cfi_flash.c
index 7faecdf..92a6567 100644
--- a/hw/cfi_flash.c
+++ b/hw/cfi_flash.c
@@ -131,6 +131,7 @@ struct cfi_flash_device {
 	u32			size;
 
 	void			*flash_memory;
+	int			flash_fd;
 	u8			program_buffer[PROGRAM_BUFF_SIZE];
 	unsigned long		*lock_bm;
 	u64			block_address;
@@ -451,7 +452,7 @@ static int map_flash_memory(struct kvm *kvm, struct cfi_flash_device *sfdev)
 	int ret;
 
 	ret = kvm__register_mem(kvm, sfdev->base_addr, sfdev->size,
-				sfdev->flash_memory,
+				sfdev->flash_memory, sfdev->flash_fd, 0,
 				KVM_MEM_TYPE_RAM | KVM_MEM_TYPE_READONLY);
 	if (!ret)
 		sfdev->is_mapped = true;
@@ -583,6 +584,7 @@ static struct cfi_flash_device *create_flash_device_file(struct kvm *kvm,
 		ret = -errno;
 		goto out_free;
 	}
+	sfdev->flash_fd = fd;
 	sfdev->base_addr = KVM_FLASH_MMIO_BASE;
 	sfdev->state = READY;
 	sfdev->read_mode = READ_ARRAY;
diff --git a/hw/vesa.c b/hw/vesa.c
index 522ffa3..277d638 100644
--- a/hw/vesa.c
+++ b/hw/vesa.c
@@ -102,7 +102,7 @@ struct framebuffer *vesa__init(struct kvm *kvm)
 		goto close_memfd;
 	}
 
-	r = kvm__register_dev_mem(kvm, VESA_MEM_ADDR, VESA_MEM_SIZE, mem);
+	r = kvm__register_dev_mem(kvm, VESA_MEM_ADDR, VESA_MEM_SIZE, mem, mem_fd, 0);
 	if (r < 0)
 		goto unmap_dev;
 
diff --git a/include/kvm/kvm.h b/include/kvm/kvm.h
index f0be524..33cae9d 100644
--- a/include/kvm/kvm.h
+++ b/include/kvm/kvm.h
@@ -135,24 +135,25 @@ bool kvm__emulate_io(struct kvm_cpu *vcpu, u16 port, void *data, int direction,
 bool kvm__emulate_mmio(struct kvm_cpu *vcpu, u64 phys_addr, u8 *data, u32 len, u8 is_write);
 int kvm__destroy_mem(struct kvm *kvm, u64 guest_phys, u64 size, void *userspace_addr);
 int kvm__register_mem(struct kvm *kvm, u64 guest_phys, u64 size, void *userspace_addr,
-		      enum kvm_mem_type type);
+		      int memfd, u64 offset, enum kvm_mem_type type);
 static inline int kvm__register_ram(struct kvm *kvm, u64 guest_phys, u64 size,
-				    void *userspace_addr)
+				    void *userspace_addr, int memfd, u64 offset)
 {
-	return kvm__register_mem(kvm, guest_phys, size, userspace_addr,
-				 KVM_MEM_TYPE_RAM);
+	return kvm__register_mem(kvm, guest_phys, size, userspace_addr, memfd,
+				 offset, KVM_MEM_TYPE_RAM);
 }
 
 static inline int kvm__register_dev_mem(struct kvm *kvm, u64 guest_phys,
-					u64 size, void *userspace_addr)
+					u64 size, void *userspace_addr,
+					int memfd, u64 offset)
 {
-	return kvm__register_mem(kvm, guest_phys, size, userspace_addr,
-				 KVM_MEM_TYPE_DEVICE);
+	return kvm__register_mem(kvm, guest_phys, size, userspace_addr, memfd,
+				 offset, KVM_MEM_TYPE_DEVICE);
 }
 
 static inline int kvm__reserve_mem(struct kvm *kvm, u64 guest_phys, u64 size)
 {
-	return kvm__register_mem(kvm, guest_phys, size, NULL,
+	return kvm__register_mem(kvm, guest_phys, size, NULL, -1, 0,
 				 KVM_MEM_TYPE_RESERVED);
 }
 
diff --git a/kvm.c b/kvm.c
index c71646f..fc0bfc4 100644
--- a/kvm.c
+++ b/kvm.c
@@ -256,7 +256,8 @@ out:
 }
 
 int kvm__register_mem(struct kvm *kvm, u64 guest_phys, u64 size,
-		      void *userspace_addr, enum kvm_mem_type type)
+		      void *userspace_addr, int memfd, u64 offset,
+		      enum kvm_mem_type type)
 {
 	struct kvm_mem_bank *merged = NULL;
 	struct kvm_mem_bank *bank;
diff --git a/mips/kvm.c b/mips/kvm.c
index 0a0d025..ebb2b19 100644
--- a/mips/kvm.c
+++ b/mips/kvm.c
@@ -38,21 +38,21 @@ void kvm__init_ram(struct kvm *kvm)
 		phys_size  = kvm->ram_size;
 		host_mem   = kvm->ram_start;
 
-		kvm__register_ram(kvm, phys_start, phys_size, host_mem);
+		kvm__register_ram(kvm, phys_start, phys_size, host_mem, kvm->ram_fd, 0);
 	} else {
 		/* one region for memory that fits below MMIO range */
 		phys_start = 0;
 		phys_size  = KVM_MMIO_START;
 		host_mem   = kvm->ram_start;
 
-		kvm__register_ram(kvm, phys_start, phys_size, host_mem);
+		kvm__register_ram(kvm, phys_start, phys_size, host_mem, kvm->ram_fd, 0);
 
 		/* one region for rest of memory */
 		phys_start = KVM_MMIO_START + KVM_MMIO_SIZE;
 		phys_size  = kvm->ram_size - KVM_MMIO_START;
 		host_mem   = kvm->ram_start + KVM_MMIO_START;
 
-		kvm__register_ram(kvm, phys_start, phys_size, host_mem);
+		kvm__register_ram(kvm, phys_start, phys_size, host_mem, kvm->ram_fd, 0);
 	}
 }
 
diff --git a/powerpc/kvm.c b/powerpc/kvm.c
index 8d467e9..c36c497 100644
--- a/powerpc/kvm.c
+++ b/powerpc/kvm.c
@@ -88,7 +88,7 @@ void kvm__init_ram(struct kvm *kvm)
 		    "overlaps MMIO!\n",
 		    phys_size);
 
-	kvm__register_ram(kvm, phys_start, phys_size, host_mem);
+	kvm__register_ram(kvm, phys_start, phys_size, host_mem, kvm->ram_fd, 0);
 }
 
 void kvm__arch_set_cmdline(char *cmdline, bool video)
diff --git a/riscv/kvm.c b/riscv/kvm.c
index 4a2a3df..bb79c5d 100644
--- a/riscv/kvm.c
+++ b/riscv/kvm.c
@@ -38,7 +38,7 @@ void kvm__init_ram(struct kvm *kvm)
 	phys_size	= kvm->ram_size;
 	host_mem	= kvm->ram_start;
 
-	err = kvm__register_ram(kvm, phys_start, phys_size, host_mem);
+	err = kvm__register_ram(kvm, phys_start, phys_size, host_mem, kvm->ram_fd, 0);
 	if (err)
 		die("Failed to register %lld bytes of memory at physical "
 		    "address 0x%llx [err %d]", phys_size, phys_start, err);
diff --git a/vfio/core.c b/vfio/core.c
index 3ff2c0b..ea189a0 100644
--- a/vfio/core.c
+++ b/vfio/core.c
@@ -255,7 +255,8 @@ int vfio_map_region(struct kvm *kvm, struct vfio_device *vdev,
 	region->host_addr = base;
 
 	ret = kvm__register_dev_mem(kvm, region->guest_phys_addr, map_size,
-				    region->host_addr);
+				    region->host_addr, vdev->fd,
+				    region->info.offset);
 	if (ret) {
 		vfio_dev_err(vdev, "failed to register region with KVM");
 		return ret;
diff --git a/x86/kvm.c b/x86/kvm.c
index 8d29904..cee82d3 100644
--- a/x86/kvm.c
+++ b/x86/kvm.c
@@ -107,7 +107,7 @@ void kvm__init_ram(struct kvm *kvm)
 		phys_size  = kvm->ram_size;
 		host_mem   = kvm->ram_start;
 
-		kvm__register_ram(kvm, phys_start, phys_size, host_mem);
+		kvm__register_ram(kvm, phys_start, phys_size, host_mem, kvm->ram_fd, 0);
 	} else {
 		/* First RAM range from zero to the PCI gap: */
 
@@ -115,7 +115,7 @@ void kvm__init_ram(struct kvm *kvm)
 		phys_size  = KVM_32BIT_GAP_START;
 		host_mem   = kvm->ram_start;
 
-		kvm__register_ram(kvm, phys_start, phys_size, host_mem);
+		kvm__register_ram(kvm, phys_start, phys_size, host_mem, kvm->ram_fd, 0);
 
 		/* Second RAM range from 4GB to the end of RAM: */
 
@@ -123,7 +123,7 @@ void kvm__init_ram(struct kvm *kvm)
 		phys_size  = kvm->ram_size - phys_start;
 		host_mem   = kvm->ram_start + phys_start;
 
-		kvm__register_ram(kvm, phys_start, phys_size, host_mem);
+		kvm__register_ram(kvm, phys_start, phys_size, host_mem, kvm->ram_fd, 0);
 	}
 }
 
-- 
2.39.0.rc0.267.gcb52ba06e7-goog

