riscv: Implement Guest/VM arch functions

This patch implements all kvm__arch_<xyz> Guest/VM arch functions.

These functions mostly deal with:
1. Guest/VM RAM initialization
2. Updating terminals on character read
3. Loading kernel and initrd images

Firmware loading is not implemented currently because initially we
will be booting kernel directly without any bootloader. In future,
we will certainly support firmware loading.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Link: https://lore.kernel.org/r/20211119124515.89439-4-anup.patel@wdc.com
Signed-off-by: Will Deacon <will@kernel.org>

2 files changed, 134 insertions, 6 deletions

diff --git a/riscv/include/kvm/kvm-arch.h b/riscv/include/kvm/kvm-arch.h
index 01d88edd..300538d8 100644
--- a/riscv/include/kvm/kvm-arch.h
+++ b/riscv/include/kvm/kvm-arch.h
@@ -55,6 +55,21 @@
 struct kvm;
 
 struct kvm_arch {
+	/*
+	 * We may have to align the guest memory for virtio, so keep the
+	 * original pointers here for munmap.
+	 */
+	void	*ram_alloc_start;
+	u64	ram_alloc_size;
+
+	/*
+	 * Guest addresses for memory layout.
+	 */
+	u64	memory_guest_start;
+	u64	kern_guest_start;
+	u64	initrd_guest_start;
+	u64	initrd_size;
+	u64	dtb_guest_start;
 };
 
 static inline bool riscv_addr_in_ioport_region(u64 phys_addr)
diff --git a/riscv/kvm.c b/riscv/kvm.c
index e816ef5c..84e02779 100644
--- a/riscv/kvm.c
+++ b/riscv/kvm.c
@@ -1,5 +1,7 @@
 #include "kvm/kvm.h"
 #include "kvm/util.h"
+#include "kvm/8250-serial.h"
+#include "kvm/virtio-console.h"
 #include "kvm/fdt.h"
 
 #include <linux/kernel.h>
@@ -19,33 +21,144 @@ bool kvm__arch_cpu_supports_vm(void)
 
 void kvm__init_ram(struct kvm *kvm)
 {
-	/* TODO: */
+	int err;
+	u64 phys_start, phys_size;
+	void *host_mem;
+
+	phys_start	= RISCV_RAM;
+	phys_size	= kvm->ram_size;
+	host_mem	= kvm->ram_start;
+
+	err = kvm__register_ram(kvm, phys_start, phys_size, host_mem);
+	if (err)
+		die("Failed to register %lld bytes of memory at physical "
+		    "address 0x%llx [err %d]", phys_size, phys_start, err);
+
+	kvm->arch.memory_guest_start = phys_start;
 }
 
 void kvm__arch_delete_ram(struct kvm *kvm)
 {
-	/* TODO: */
+	munmap(kvm->arch.ram_alloc_start, kvm->arch.ram_alloc_size);
 }
 
 void kvm__arch_read_term(struct kvm *kvm)
 {
-	/* TODO: */
+	serial8250__update_consoles(kvm);
+	virtio_console__inject_interrupt(kvm);
 }
 
 void kvm__arch_set_cmdline(char *cmdline, bool video)
 {
-	/* TODO: */
 }
 
 void kvm__arch_init(struct kvm *kvm, const char *hugetlbfs_path, u64 ram_size)
 {
-	/* TODO: */
+	/*
+	 * Allocate guest memory. We must align our buffer to 64K to
+	 * correlate with the maximum guest page size for virtio-mmio.
+	 * If using THP, then our minimal alignment becomes 2M.
+	 * 2M trumps 64K, so let's go with that.
+	 */
+	kvm->ram_size = min(ram_size, (u64)RISCV_MAX_MEMORY(kvm));
+	kvm->arch.ram_alloc_size = kvm->ram_size + SZ_2M;
+	kvm->arch.ram_alloc_start = mmap_anon_or_hugetlbfs(kvm, hugetlbfs_path,
+						kvm->arch.ram_alloc_size);
+
+	if (kvm->arch.ram_alloc_start == MAP_FAILED)
+		die("Failed to map %lld bytes for guest memory (%d)",
+		    kvm->arch.ram_alloc_size, errno);
+
+	kvm->ram_start = (void *)ALIGN((unsigned long)kvm->arch.ram_alloc_start,
+					SZ_2M);
+
+	madvise(kvm->arch.ram_alloc_start, kvm->arch.ram_alloc_size,
+		MADV_MERGEABLE);
+
+	madvise(kvm->arch.ram_alloc_start, kvm->arch.ram_alloc_size,
+		MADV_HUGEPAGE);
 }
 
+#define FDT_ALIGN	SZ_4M
+#define INITRD_ALIGN	8
 bool kvm__arch_load_kernel_image(struct kvm *kvm, int fd_kernel, int fd_initrd,
 				 const char *kernel_cmdline)
 {
-	/* TODO: */
+	void *pos, *kernel_end, *limit;
+	unsigned long guest_addr, kernel_offset;
+	ssize_t file_size;
+
+	/*
+	 * Linux requires the initrd and dtb to be mapped inside lowmem,
+	 * so we can't just place them at the top of memory.
+	 */
+	limit = kvm->ram_start + min(kvm->ram_size, (u64)SZ_256M) - 1;
+
+#if __riscv_xlen == 64
+	/* Linux expects to be booted at 2M boundary for RV64 */
+	kernel_offset = 0x200000;
+#else
+	/* Linux expects to be booted at 4M boundary for RV32 */
+	kernel_offset = 0x400000;
+#endif
+
+	pos = kvm->ram_start + kernel_offset;
+	kvm->arch.kern_guest_start = host_to_guest_flat(kvm, pos);
+	file_size = read_file(fd_kernel, pos, limit - pos);
+	if (file_size < 0) {
+		if (errno == ENOMEM)
+			die("kernel image too big to fit in guest memory.");
+
+		die_perror("kernel read");
+	}
+	kernel_end = pos + file_size;
+	pr_debug("Loaded kernel to 0x%llx (%zd bytes)",
+		 kvm->arch.kern_guest_start, file_size);
+
+	/* Place FDT just after kernel at FDT_ALIGN address */
+	pos = kernel_end + FDT_ALIGN;
+	guest_addr = ALIGN(host_to_guest_flat(kvm, pos), FDT_ALIGN);
+	pos = guest_flat_to_host(kvm, guest_addr);
+	if (pos < kernel_end)
+		die("fdt overlaps with kernel image.");
+
+	kvm->arch.dtb_guest_start = guest_addr;
+	pr_debug("Placing fdt at 0x%llx - 0x%llx",
+		 kvm->arch.dtb_guest_start,
+		 host_to_guest_flat(kvm, limit));
+
+	/* ... and finally the initrd, if we have one. */
+	if (fd_initrd != -1) {
+		struct stat sb;
+		unsigned long initrd_start;
+
+		if (fstat(fd_initrd, &sb))
+			die_perror("fstat");
+
+		pos = limit - (sb.st_size + INITRD_ALIGN);
+		guest_addr = ALIGN(host_to_guest_flat(kvm, pos), INITRD_ALIGN);
+		pos = guest_flat_to_host(kvm, guest_addr);
+		if (pos < kernel_end)
+			die("initrd overlaps with kernel image.");
+
+		initrd_start = guest_addr;
+		file_size = read_file(fd_initrd, pos, limit - pos);
+		if (file_size == -1) {
+			if (errno == ENOMEM)
+				die("initrd too big to fit in guest memory.");
+
+			die_perror("initrd read");
+		}
+
+		kvm->arch.initrd_guest_start = initrd_start;
+		kvm->arch.initrd_size = file_size;
+		pr_debug("Loaded initrd to 0x%llx (%llu bytes)",
+			 kvm->arch.initrd_guest_start,
+			 kvm->arch.initrd_size);
+	} else {
+		kvm->arch.initrd_size = 0;
+	}
+
 	return true;
 }