linux-kernel - [kvmtool hack 2/3] kvmtool: arm64: Add support for guest physical address size

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Message-Id: <20180109190414.4017-19-suzuki.poulose@arm.com>
Date:   Tue,  9 Jan 2018 19:04:13 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu,
        christoffer.dall@...aro.org, marc.zyngier@....com,
        linux-kernel@...r.kernel.org, kristina.martsenko@....com,
        peter.maydell@...aro.org, suzuki.poulose@....com,
        pbonzini@...hat.com, rkrcmar@...hat.com, will.deacon@....com,
        ard.biesheuvel@...aro.org, mark.rutland@....com,
        catalin.marinas@....com
Subject: [kvmtool hack 2/3] kvmtool: arm64: Add support for guest physical address size

Add an option to specify the physical address size used by this
VM.

Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 arm/aarch64/include/kvm/kvm-config-arch.h |  5 ++++-
 arm/include/arm-common/kvm-config-arch.h  |  1 +
 arm/kvm.c                                 | 30 ++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/arm/aarch64/include/kvm/kvm-config-arch.h b/arm/aarch64/include/kvm/kvm-config-arch.h
index 04be43d..c4bb207 100644
--- a/arm/aarch64/include/kvm/kvm-config-arch.h
+++ b/arm/aarch64/include/kvm/kvm-config-arch.h
@@ -8,7 +8,10 @@
 			"Create PMUv3 device"),				\
 	OPT_U64('\0', "kaslr-seed", &(cfg)->kaslr_seed,			\
 			"Specify random seed for Kernel Address Space "	\
-			"Layout Randomization (KASLR)"),
+			"Layout Randomization (KASLR)"),		\
+	OPT_UINTEGER('\0', "phys-shift", &(cfg)->phys_shift,		\
+			"Specify maximum physical address size (not "	\
+			"the amount of memory)"),
 
 #include "arm-common/kvm-config-arch.h"
 
diff --git a/arm/include/arm-common/kvm-config-arch.h b/arm/include/arm-common/kvm-config-arch.h
index 6a196f1..d841b0b 100644
--- a/arm/include/arm-common/kvm-config-arch.h
+++ b/arm/include/arm-common/kvm-config-arch.h
@@ -11,6 +11,7 @@ struct kvm_config_arch {
 	bool		has_pmuv3;
 	u64		kaslr_seed;
 	enum irqchip_type irqchip;
+	unsigned int	phys_shift;
 };
 
 int irqchip_parser(const struct option *opt, const char *arg, int unset);
diff --git a/arm/kvm.c b/arm/kvm.c
index 2ab436e..7573391 100644
--- a/arm/kvm.c
+++ b/arm/kvm.c
@@ -18,6 +18,14 @@ struct kvm_ext kvm_req_ext[] = {
 	{ 0, 0 },
 };
 
+#ifndef KVM_CAP_ARM_CONFIG_PHYS_SHIFT
+#define KVM_CAP_ARM_CONFIG_PHYS_SHIFT	151
+#endif
+
+#ifndef KVM_ARM_SET_PHYS_SIZE
+#define KVM_ARM_SET_PHYS_SIZE		_IOW(KVMIO, 0xb2, __u32)
+#endif
+
 bool kvm__arch_cpu_supports_vm(void)
 {
 	/* The KVM capability check is enough. */
@@ -57,8 +65,30 @@ void kvm__arch_set_cmdline(char *cmdline, bool video)
 {
 }
 
+static void kvm__init_phys_size(struct kvm *kvm)
+{
+	if (!kvm->cfg.arch.phys_shift)
+		goto default_phys_size;
+	if (kvm->cfg.arch.phys_shift > 48)
+		die("Physical memory size is limited to 48bits, %d\n",
+			kvm->cfg.arch.phys_shift);
+
+	if (!kvm__supports_extension(kvm, KVM_CAP_ARM_CONFIG_PHYS_SHIFT)) {
+		pr_warning("System doesn't support phys size configuration\n");
+		goto default_phys_size;
+	}
+	if (ioctl(kvm->vm_fd, KVM_ARM_SET_PHYS_SIZE, &kvm->cfg.arch.phys_shift))
+		die("Failed to set physical memory size to %dbits\n",
+			kvm->cfg.arch.phys_shift);
+	return;
+default_phys_size:
+	kvm->cfg.arch.phys_shift = 40;
+	return;
+}
+
 void kvm__arch_init(struct kvm *kvm, const char *hugetlbfs_path, u64 ram_size)
 {
+	kvm__init_phys_size(kvm);
 	/*
 	 * Allocate guest memory. We must align our buffer to 64K to
 	 * correlate with the maximum guest page size for virtio-mmio.
-- 
2.13.6