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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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a28e4f5a62
Add basic KVM paravirt support. Avoid vm-exits on IO delays. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
132 lines
3.1 KiB
C
132 lines
3.1 KiB
C
#ifndef __X86_KVM_PARA_H
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#define __X86_KVM_PARA_H
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/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx. It
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* should be used to determine that a VM is running under KVM.
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*/
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#define KVM_CPUID_SIGNATURE 0x40000000
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/* This CPUID returns a feature bitmap in eax. Before enabling a particular
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* paravirtualization, the appropriate feature bit should be checked.
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*/
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#define KVM_CPUID_FEATURES 0x40000001
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#define KVM_FEATURE_CLOCKSOURCE 0
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#define KVM_FEATURE_NOP_IO_DELAY 1
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#define MSR_KVM_WALL_CLOCK 0x11
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#define MSR_KVM_SYSTEM_TIME 0x12
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#ifdef __KERNEL__
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#include <asm/processor.h>
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/* xen binary-compatible interface. See xen headers for details */
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struct kvm_vcpu_time_info {
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uint32_t version;
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uint32_t pad0;
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uint64_t tsc_timestamp;
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uint64_t system_time;
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uint32_t tsc_to_system_mul;
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int8_t tsc_shift;
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int8_t pad[3];
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} __attribute__((__packed__)); /* 32 bytes */
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struct kvm_wall_clock {
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uint32_t wc_version;
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uint32_t wc_sec;
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uint32_t wc_nsec;
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} __attribute__((__packed__));
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extern void kvmclock_init(void);
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/* This instruction is vmcall. On non-VT architectures, it will generate a
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* trap that we will then rewrite to the appropriate instruction.
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*/
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#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
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/* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
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* instruction. The hypervisor may replace it with something else but only the
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* instructions are guaranteed to be supported.
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*
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* Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
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* The hypercall number should be placed in rax and the return value will be
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* placed in rax. No other registers will be clobbered unless explicited
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* noted by the particular hypercall.
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*/
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static inline long kvm_hypercall0(unsigned int nr)
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{
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long ret;
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asm volatile(KVM_HYPERCALL
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: "=a"(ret)
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: "a"(nr));
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return ret;
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}
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static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
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{
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long ret;
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asm volatile(KVM_HYPERCALL
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: "=a"(ret)
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: "a"(nr), "b"(p1));
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return ret;
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}
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static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
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unsigned long p2)
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{
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long ret;
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asm volatile(KVM_HYPERCALL
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: "=a"(ret)
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: "a"(nr), "b"(p1), "c"(p2));
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return ret;
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}
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static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
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unsigned long p2, unsigned long p3)
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{
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long ret;
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asm volatile(KVM_HYPERCALL
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: "=a"(ret)
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: "a"(nr), "b"(p1), "c"(p2), "d"(p3));
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return ret;
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}
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static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
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unsigned long p2, unsigned long p3,
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unsigned long p4)
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{
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long ret;
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asm volatile(KVM_HYPERCALL
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: "=a"(ret)
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: "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4));
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return ret;
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}
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static inline int kvm_para_available(void)
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{
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unsigned int eax, ebx, ecx, edx;
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char signature[13];
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cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
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memcpy(signature + 0, &ebx, 4);
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memcpy(signature + 4, &ecx, 4);
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memcpy(signature + 8, &edx, 4);
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signature[12] = 0;
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if (strcmp(signature, "KVMKVMKVM") == 0)
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return 1;
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return 0;
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}
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static inline unsigned int kvm_arch_para_features(void)
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{
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return cpuid_eax(KVM_CPUID_FEATURES);
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}
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#endif
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#endif
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