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| author | Joao Martins <joao.m.martins@oracle.com> | 2018-06-13 16:55:44 +0300 |
|---|---|---|
| committer | David Woodhouse <dwmw@amazon.co.uk> | 2021-02-04 17:19:24 +0300 |
| commit | 79033bebf6fa3045bfa9bbe543c0eb7b43a0f4a3 (patch) | |
| tree | 7b1eebd8240021a79f43d43161f69667a1a72863 /arch/x86/kvm/hyperv.c | |
| parent | 23200b7a30de315d0e9a40663c905869d29d833c (diff) | |
| download | linux-79033bebf6fa3045bfa9bbe543c0eb7b43a0f4a3.tar.xz | |
KVM: x86/xen: Fix coexistence of Xen and Hyper-V hypercalls
Disambiguate Xen vs. Hyper-V calls by adding 'orl $0x80000000, %eax'
at the start of the Hyper-V hypercall page when Xen hypercalls are
also enabled.
That bit is reserved in the Hyper-V ABI, and those hypercall numbers
will never be used by Xen (because it does precisely the same trick).
Switch to using kvm_vcpu_write_guest() while we're at it, instead of
open-coding it.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Diffstat (limited to 'arch/x86/kvm/hyperv.c')
| -rw-r--r-- | arch/x86/kvm/hyperv.c | 40 |
1 files changed, 29 insertions, 11 deletions
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 5c45d80a7ce3..af7278abe16b 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -23,6 +23,7 @@ #include "ioapic.h" #include "cpuid.h" #include "hyperv.h" +#include "xen.h" #include <linux/cpu.h> #include <linux/kvm_host.h> @@ -1139,9 +1140,9 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data, hv->hv_hypercall &= ~HV_X64_MSR_HYPERCALL_ENABLE; break; case HV_X64_MSR_HYPERCALL: { - u64 gfn; - unsigned long addr; - u8 instructions[4]; + u8 instructions[9]; + int i = 0; + u64 addr; /* if guest os id is not set hypercall should remain disabled */ if (!hv->hv_guest_os_id) @@ -1150,16 +1151,33 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data, hv->hv_hypercall = data; break; } - gfn = data >> HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT; - addr = gfn_to_hva(kvm, gfn); - if (kvm_is_error_hva(addr)) - return 1; - static_call(kvm_x86_patch_hypercall)(vcpu, instructions); - ((unsigned char *)instructions)[3] = 0xc3; /* ret */ - if (__copy_to_user((void __user *)addr, instructions, 4)) + + /* + * If Xen and Hyper-V hypercalls are both enabled, disambiguate + * the same way Xen itself does, by setting the bit 31 of EAX + * which is RsvdZ in the 32-bit Hyper-V hypercall ABI and just + * going to be clobbered on 64-bit. + */ + if (kvm_xen_hypercall_enabled(kvm)) { + /* orl $0x80000000, %eax */ + instructions[i++] = 0x0d; + instructions[i++] = 0x00; + instructions[i++] = 0x00; + instructions[i++] = 0x00; + instructions[i++] = 0x80; + } + + /* vmcall/vmmcall */ + static_call(kvm_x86_patch_hypercall)(vcpu, instructions + i); + i += 3; + + /* ret */ + ((unsigned char *)instructions)[i++] = 0xc3; + + addr = data & HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK; + if (kvm_vcpu_write_guest(vcpu, addr, instructions, i)) return 1; hv->hv_hypercall = data; - mark_page_dirty(kvm, gfn); break; } case HV_X64_MSR_REFERENCE_TSC: |