github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-31 10:33:41 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

KVM: x86: Add helpers to prepare kvm_run for userspace MMIO exit

Browse Source 
Add helpers to fill kvm_run for userspace MMIO exits to deduplicate a
variety of code, and to allow for a cleaner return path in
emulator_read_write().

Opportunistically add a KVM_BUG_ON() to ensure the caller is limiting the
length of a single MMIO access to 8 bytes (the largest size userspace is
prepared to handled, as the ABI was baked before things like MOVDQ came
along).

No functional change intended.

Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Binbin Wu <binbin.wu@linux.intel.com>
Cc: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Michael Roth <michael.roth@amd.com>
Tested-by: Tom Lendacky <thomas.lendacky@gmail.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Link: https://patch.msgid.link/20260225012049.920665-15-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2026-02-24 17:20:49 -08:00
parent 4f09e62afc
commit e2138c4a5b
3 changed files with 38 additions and 44 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
arch/x86/kvm/vmx/tdx.c
View File

@ -1467,17 +1467,11 @@ static int tdx_emulate_mmio(struct kvm_vcpu *vcpu)
/* Request the device emulation to userspace device model. */
vcpu->mmio_is_write = write;
if (!write)
__kvm_prepare_emulated_mmio_exit(vcpu, gpa, size, &val, write);
if (!write) {
vcpu->arch.complete_userspace_io = tdx_complete_mmio_read;
vcpu->run->mmio.phys_addr = gpa;
vcpu->run->mmio.len = size;
vcpu->run->mmio.is_write = write;
vcpu->run->exit_reason = KVM_EXIT_MMIO;
if (write) {
memcpy(vcpu->run->mmio.data, &val, size);
} else {
vcpu->mmio_fragments[0].gpa = gpa;
vcpu->mmio_fragments[0].len = size;
trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, size, gpa, NULL);

42
arch/x86/kvm/x86.c
View File

@ -8209,7 +8209,6 @@ static int emulator_read_write(struct x86_emulate_ctxt *ctxt,
const struct read_write_emulator_ops *ops)
{
struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
struct kvm_mmio_fragment *frag;
int rc;
if (WARN_ON_ONCE((bytes > 8u || !ops->write) && object_is_on_stack(val)))
@ -8267,12 +8266,9 @@ static int emulator_read_write(struct x86_emulate_ctxt *ctxt,
vcpu->mmio_needed = 1;
vcpu->mmio_cur_fragment = 0;
vcpu->mmio_is_write = ops->write;
frag = &vcpu->mmio_fragments[0];
vcpu->run->mmio.len = min(8u, frag->len);
vcpu->run->mmio.is_write = vcpu->mmio_is_write = ops->write;
vcpu->run->exit_reason = KVM_EXIT_MMIO;
vcpu->run->mmio.phys_addr = frag->gpa;
kvm_prepare_emulated_mmio_exit(vcpu, &vcpu->mmio_fragments[0]);
/*
* For MMIO reads, stop emulating and immediately exit to userspace, as
@ -8282,11 +8278,7 @@ static int emulator_read_write(struct x86_emulate_ctxt *ctxt,
* after completing emulation (see the check on vcpu->mmio_needed in
* x86_emulate_instruction()).
*/
if (!ops->write)
return X86EMUL_IO_NEEDED;
memcpy(vcpu->run->mmio.data, frag->data, min(8u, frag->len));
return X86EMUL_CONTINUE;
return ops->write ? X86EMUL_CONTINUE : X86EMUL_IO_NEEDED;
}
static int emulator_read_emulated(struct x86_emulate_ctxt *ctxt,
@ -11883,12 +11875,7 @@ static int complete_emulated_mmio(struct kvm_vcpu *vcpu)
return complete_emulated_io(vcpu);
}
run->exit_reason = KVM_EXIT_MMIO;
run->mmio.phys_addr = frag->gpa;
if (vcpu->mmio_is_write)
memcpy(run->mmio.data, frag->data, min(8u, frag->len));
run->mmio.len = min(8u, frag->len);
run->mmio.is_write = vcpu->mmio_is_write;
kvm_prepare_emulated_mmio_exit(vcpu, frag);
vcpu->arch.complete_userspace_io = complete_emulated_mmio;
return 0;
}
@ -14295,15 +14282,8 @@ static int complete_sev_es_emulated_mmio(struct kvm_vcpu *vcpu)
}
// More MMIO is needed
run->mmio.phys_addr = frag->gpa;
run->mmio.len = min(8u, frag->len);
run->mmio.is_write = vcpu->mmio_is_write;
if (run->mmio.is_write)
memcpy(run->mmio.data, frag->data, min(8u, frag->len));
run->exit_reason = KVM_EXIT_MMIO;
kvm_prepare_emulated_mmio_exit(vcpu, frag);
vcpu->arch.complete_userspace_io = complete_sev_es_emulated_mmio;
return 0;
}
@ -14332,23 +14312,17 @@ int kvm_sev_es_mmio(struct kvm_vcpu *vcpu, bool is_write, gpa_t gpa,
* requests that split a page boundary.
*/
frag = vcpu->mmio_fragments;
vcpu->mmio_nr_fragments = 1;
frag->len = bytes;
frag->gpa = gpa;
frag->data = data;
vcpu->mmio_needed = 1;
vcpu->mmio_cur_fragment = 0;
vcpu->mmio_nr_fragments = 1;
vcpu->mmio_is_write = is_write;
vcpu->run->mmio.phys_addr = gpa;
vcpu->run->mmio.len = min(8u, frag->len);
vcpu->run->mmio.is_write = is_write;
if (is_write)
memcpy(vcpu->run->mmio.data, frag->data, min(8u, frag->len));
vcpu->run->exit_reason = KVM_EXIT_MMIO;
kvm_prepare_emulated_mmio_exit(vcpu, frag);
vcpu->arch.complete_userspace_io = complete_sev_es_emulated_mmio;
return 0;
}
EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_sev_es_mmio);

26
arch/x86/kvm/x86.h
View File

@ -718,6 +718,32 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size,
unsigned int port, void *data, unsigned int count,
int in);
static inline void __kvm_prepare_emulated_mmio_exit(struct kvm_vcpu *vcpu,
gpa_t gpa, unsigned int len,
const void *data,
bool is_write)
{
struct kvm_run *run = vcpu->run;
KVM_BUG_ON(len > 8, vcpu->kvm);
run->mmio.len = len;
run->mmio.is_write = is_write;
run->exit_reason = KVM_EXIT_MMIO;
run->mmio.phys_addr = gpa;
if (is_write)
memcpy(run->mmio.data, data, len);
}
static inline void kvm_prepare_emulated_mmio_exit(struct kvm_vcpu *vcpu,
struct kvm_mmio_fragment *frag)
{
WARN_ON_ONCE(!vcpu->mmio_needed || !vcpu->mmio_nr_fragments);
__kvm_prepare_emulated_mmio_exit(vcpu, frag->gpa, min(8u, frag->len),
frag->data, vcpu->mmio_is_write);
}
static inline bool user_exit_on_hypercall(struct kvm *kvm, unsigned long hc_nr)
{
return kvm->arch.hypercall_exit_enabled & BIT(hc_nr);