[RFC,kvmtool,v1,11/32] Allocate vesa memory with memfd

Commit Message

Fuad Tabba Dec. 2, 2022, 5:43 p.m. UTC

Ensure that all guest memory is fd-based.

Signed-off-by: Fuad Tabba <[e-mail]>
---
 framebuffer.c             |  2 ++
 hw/vesa.c                 | 15 +++++++++++++--
 include/kvm/framebuffer.h |  1 +
 3 files changed, 16 insertions(+), 2 deletions(-)

Patch

diff --git a/framebuffer.c b/framebuffer.c
index fb8f51d..a025293 100644
--- a/framebuffer.c
+++ b/framebuffer.c
@@ -73,6 +73,8 @@  int fb__exit(struct kvm *kvm)
 				fb->targets[i]->stop(fb);
 
 		munmap(fb->mem, fb->mem_size);
+		if (fb->mem_fd >= 0)
+			close(fb->mem_fd);
 	}
 
 	return 0;
diff --git a/hw/vesa.c b/hw/vesa.c
index 7f82cdb..522ffa3 100644
--- a/hw/vesa.c
+++ b/hw/vesa.c
@@ -41,6 +41,7 @@  static struct framebuffer vesafb = {
 	.depth		= VESA_BPP,
 	.mem_addr	= VESA_MEM_ADDR,
 	.mem_size	= VESA_MEM_SIZE,
+	.mem_fd		= -1,
 };
 
 static void vesa_pci_io(struct kvm_cpu *vcpu, u64 addr, u8 *data, u32 len,
@@ -66,6 +67,7 @@  struct framebuffer *vesa__init(struct kvm *kvm)
 {
 	u16 vesa_base_addr;
 	char *mem;
+	int mem_fd;
 	int r;
 
 	BUILD_BUG_ON(!is_power_of_two(VESA_MEM_SIZE));
@@ -88,22 +90,31 @@  struct framebuffer *vesa__init(struct kvm *kvm)
 	if (r < 0)
 		goto unregister_ioport;
 
-	mem = mmap(NULL, VESA_MEM_SIZE, PROT_RW, MAP_ANON_NORESERVE, -1, 0);
-	if (mem == MAP_FAILED) {
+	mem_fd = memfd_alloc(ARM_PVTIME_SIZE, false, 0, 0);
+	if (mem_fd < 0) {
 		r = -errno;
 		goto unregister_device;
 	}
 
+	mem = mmap(NULL, VESA_MEM_SIZE, PROT_RW, MAP_PRIVATE, mem_fd, 0);
+	if (mem == MAP_FAILED) {
+		r = -errno;
+		goto close_memfd;
+	}
+
 	r = kvm__register_dev_mem(kvm, VESA_MEM_ADDR, VESA_MEM_SIZE, mem);
 	if (r < 0)
 		goto unmap_dev;
 
 	vesafb.mem = mem;
+	vesafb.mem_fd = mem_fd;
 	vesafb.kvm = kvm;
 	return fb__register(&vesafb);
 
 unmap_dev:
 	munmap(mem, VESA_MEM_SIZE);
+close_memfd:
+	close(mem_fd);
 unregister_device:
 	device__unregister(&vesa_device);
 unregister_ioport:
diff --git a/include/kvm/framebuffer.h b/include/kvm/framebuffer.h
index e3200e5..c340273 100644
--- a/include/kvm/framebuffer.h
+++ b/include/kvm/framebuffer.h
@@ -22,6 +22,7 @@  struct framebuffer {
 	char				*mem;
 	u64				mem_addr;
 	u64				mem_size;
+	int				mem_fd;
 	struct kvm			*kvm;
 
 	unsigned long			nr_targets;