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KVM: SEV-ES: go over the sev_pio_data buffer in multiple passes if needed
The PIO scratch buffer is larger than a single page, and therefore
it is not possible to copy it in a single step to vcpu->arch/pio_data.
Bound each call to emulator_pio_in/out to a single page; keep
track of how many I/O operations are left in vcpu->arch.sev_pio_count,
so that the operation can be restarted in the complete_userspace_io
callback.
For OUT, this means that the previous kvm_sev_es_outs implementation
becomes an iterator of the loop, and we can consume the sev_pio_data
buffer before leaving to userspace.
For IN, instead, consuming the buffer and decreasing sev_pio_count
is always done in the complete_userspace_io callback, because that
is when the memcpy is done into sev_pio_data.
Cc: stable@vger.kernel.org
Fixes: 7ed9abfe8e
("KVM: SVM: Support string IO operations for an SEV-ES guest")
Reported-by: Felix Wilhelm <fwilhelm@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
parent
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@ -703,6 +703,7 @@ struct kvm_vcpu_arch {
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struct kvm_pio_request pio;
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void *pio_data;
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void *sev_pio_data;
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unsigned sev_pio_count;
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u8 event_exit_inst_len;
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@ -12386,38 +12386,77 @@ int kvm_sev_es_mmio_read(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned int bytes,
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EXPORT_SYMBOL_GPL(kvm_sev_es_mmio_read);
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static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size,
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unsigned int port, unsigned int count)
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{
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int ret = emulator_pio_out(vcpu, size, port,
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vcpu->arch.sev_pio_data, count);
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unsigned int port);
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if (ret) {
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/* Emulation done by the kernel. */
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return ret;
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}
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static int complete_sev_es_emulated_outs(struct kvm_vcpu *vcpu)
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{
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int size = vcpu->arch.pio.size;
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int port = vcpu->arch.pio.port;
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vcpu->arch.pio.count = 0;
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if (vcpu->arch.sev_pio_count)
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return kvm_sev_es_outs(vcpu, size, port);
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return 1;
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}
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static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size,
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unsigned int port)
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{
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for (;;) {
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unsigned int count =
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min_t(unsigned int, PAGE_SIZE / size, vcpu->arch.sev_pio_count);
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int ret = emulator_pio_out(vcpu, size, port, vcpu->arch.sev_pio_data, count);
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/* memcpy done already by emulator_pio_out. */
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vcpu->arch.sev_pio_count -= count;
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vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size;
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if (!ret)
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break;
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/* Emulation done by the kernel. */
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if (!vcpu->arch.sev_pio_count)
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return 1;
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}
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vcpu->arch.complete_userspace_io = complete_sev_es_emulated_outs;
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return 0;
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}
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static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size,
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unsigned int port);
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static void advance_sev_es_emulated_ins(struct kvm_vcpu *vcpu)
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{
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unsigned count = vcpu->arch.pio.count;
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complete_emulator_pio_in(vcpu, vcpu->arch.sev_pio_data);
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vcpu->arch.sev_pio_count -= count;
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vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size;
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}
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static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu)
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{
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memcpy(vcpu->arch.sev_pio_data, vcpu->arch.pio_data,
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vcpu->arch.pio.count * vcpu->arch.pio.size);
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vcpu->arch.pio.count = 0;
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int size = vcpu->arch.pio.size;
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int port = vcpu->arch.pio.port;
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advance_sev_es_emulated_ins(vcpu);
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if (vcpu->arch.sev_pio_count)
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return kvm_sev_es_ins(vcpu, size, port);
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return 1;
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}
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static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size,
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unsigned int port, unsigned int count)
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unsigned int port)
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{
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int ret = emulator_pio_in(vcpu, size, port,
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vcpu->arch.sev_pio_data, count);
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for (;;) {
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unsigned int count =
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min_t(unsigned int, PAGE_SIZE / size, vcpu->arch.sev_pio_count);
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if (!__emulator_pio_in(vcpu, size, port, count))
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break;
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if (ret) {
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/* Emulation done by the kernel. */
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return ret;
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advance_sev_es_emulated_ins(vcpu);
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if (!vcpu->arch.sev_pio_count)
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return 1;
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}
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vcpu->arch.complete_userspace_io = complete_sev_es_emulated_ins;
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@ -12429,8 +12468,9 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size,
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int in)
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{
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vcpu->arch.sev_pio_data = data;
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return in ? kvm_sev_es_ins(vcpu, size, port, count)
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: kvm_sev_es_outs(vcpu, size, port, count);
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vcpu->arch.sev_pio_count = count;
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return in ? kvm_sev_es_ins(vcpu, size, port)
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: kvm_sev_es_outs(vcpu, size, port);
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}
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EXPORT_SYMBOL_GPL(kvm_sev_es_string_io);
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