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RISC-V: KVM: Add extensible CSR emulation framework

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We add an extensible CSR emulation framework which is based upon the
existing system instruction emulation. This will be useful to upcoming
AIA, PMU, Nested and other virtualization features.

The CSR emulation framework also has provision to emulate CSR in user
space but this will be used only in very specific cases such as AIA
IMSIC CSR emulation in user space or vendor specific CSR emulation
in user space.

By default, all CSRs not handled by KVM RISC-V will be redirected back
to Guest VCPU as illegal instruction trap.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Anup Patel 2022-07-29 17:14:53 +05:30 • committed by Anup Patel
parent 1222b55cee
commit 8a061562e2
5 changed files with 209 additions and 16 deletions
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8
include/uapi/linux/kvm.h
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@ -270,6 +270,7 @@ struct kvm_xen_exit {
#define KVM_EXIT_X86_BUS_LOCK 33
#define KVM_EXIT_XEN 34
#define KVM_EXIT_RISCV_SBI 35
#define KVM_EXIT_RISCV_CSR 36
/* For KVM_EXIT_INTERNAL_ERROR */
/* Emulate instruction failed. */
@ -496,6 +497,13 @@ struct kvm_run {
unsigned long args[6];
unsigned long ret[2];
} riscv_sbi;
/* KVM_EXIT_RISCV_CSR */
struct {
unsigned long csr_num;
unsigned long new_value;
unsigned long write_mask;
unsigned long ret_value;
} riscv_csr;
/* Fix the size of the union. */
char padding[256];
};